United Ireland

United Ireland, also referred to as Irish reunification, is the proposition that all of Ireland should be a single sovereign state. At present, the island is divided politically; the sovereign Republic of Ireland has jurisdiction over the majority of Ireland, while Northern Ireland, which lies entirely within (but does not constitute the entirety of) Ulster, is part of the United Kingdom. Achieving a united Ireland is a central tenet of Irish nationalism, particularly of both mainstream and dissident Irish republican political and paramilitary organisations. Unionists support Northern Ireland remaining part of the United Kingdom, and therefore oppose Irish unification.
Ireland has been partitioned since May 1921, when the implementation of the Government of Ireland Act 1920 created the state of Northern Ireland within the United Kingdom. The Anglo-Irish Treaty, which led to the establishment in December 1922 of a dominion called the Irish Free State, recognised partition, but this was opposed by anti-Treaty republicans. When the anti-Treaty Fianna Fáil party came to power in the 1930s, it adopted a new constitution which claimed sovereignty over the entire island. The Irish Republican Army (IRA) had a united Ireland as its goal during the conflict with British security forces and loyalist paramilitaries from the 1960s to the 1990s known as The Troubles. The Good Friday Agreement signed in 1998, which ended the conflict, acknowledged the legitimacy of the desire for a united Ireland, while declaring that it could be achieved only with the consent of a majority of the people of Northern Ireland.
In 2016, Sinn Féin called for a referendum on a united Ireland in the wake of the decision by the United Kingdom to leave the European Union (EU). The decision has increased the perceived likelihood of a united Ireland, in order to avoid the requirement for a possible hard border between Northern Ireland and the Republic of Ireland. Taoiseach Enda Kenny said that in the event of reunification, Northern Ireland should be allowed to rejoin the EU, just as East Germany was permitted to join the EU's predecessor institutions by reuniting with the rest of Germany after the fall of the Berlin Wall.
In demographic terms, the six counties of Northern Ireland taken as a whole contain a plurality of Ulster Protestants who almost all favour continued union with Great Britain, although individually four of the six counties have Irish Catholic majorities and majorities voting for Irish nationalist parties. The religious denominations of the citizens of Northern Ireland are only a generalised guide to likely political preferences, as there are both Protestant nationalists and Catholic unionists. Surveys identify a significant number of Catholics who favour the continuation of the union without identifying themselves as Unionists or British.
Legal basis.
Article 3.1 of the Constitution of Ireland "recognises that a united Ireland shall be brought about only by peaceful means with the consent of a majority of the people, democratically expressed, in both jurisdictions in the island". This provision was introduced in 1999 after implementation of the Good Friday Agreement, as part of replacing the old Articles 2 and 3, which had laid a direct claim to the whole island as the national territory.
The Northern Ireland Act 1998, a statute of the Parliament of the United Kingdom, provides that Northern Ireland will remain within the United Kingdom unless a majority of the people of Northern Ireland vote to form part of a united Ireland. It specifies that the Secretary of State for Northern Ireland "shall exercise the power [to hold a referendum] if at any time it appears likely to him that a majority of those voting would express a wish that Northern Ireland should cease to be part of the United Kingdom and form part of a united Ireland". Such referenda may not take place within seven years of each other.
The Northern Ireland Act 1998 supersedes previous similar legislative provisions. The Northern Ireland Constitution Act 1973 also provided that Northern Ireland remained part of the United Kingdom unless a majority voted otherwise in a referendum, while under the Ireland Act 1949 the consent of the Parliament of Northern Ireland was needed for a united Ireland. In 1985, the Anglo-Irish Agreement affirmed that any change in the status of Northern Ireland would only come about with the consent of a majority of the people of Northern Ireland.
History.
Home Rule, Resistance and the Easter Rising.
The Kingdom of Ireland as a whole had become part of the United Kingdom of Great Britain and Ireland under the Acts of Union 1800. From the 1870s, support for some form of an elected parliament in Dublin grew. In 1870, Isaac Butt, who was a Protestant, formed the Home Government Association, which became the Home Rule League. Charles Stewart Parnell, also a Protestant, became leader in 1880, and the organisation became the Irish National League in 1882. Despite the religion of its early leaders, its support was strongly associated with Irish Catholics. In 1886, Parnell formed a parliamentary alliance with Liberal Party Prime Minister William Ewart Gladstone and secured the introduction of the First Home Rule Bill. This was opposed by the Conservative Party and led to a split in the Liberal Party. Opposition in Ireland was concentrated in the heavily Protestant counties in Ulster. The difference in religious background was a legacy of the Ulster Plantation in the early seventeenth century. In 1893, the Second Home Rule Bill passed in the House of Commons, but was defeated in the House of Lords, where the Conservatives dominated. A Third Home Rule Bill was introduced in 1912, and in September 1912, just under half a million men and women signed the Ulster Covenant to swear they would resist its application in Ulster. The Ulster Volunteer Force were formed in 1913 as a militia to resist Home Rule.
The Government of Ireland Act 1914 (previously known as the Third Home Rule Bill) provided for a unitary devolved Irish Parliament, a culmination of several decades of work from the Irish Parliamentary Party. It was signed into law in September 1914 in the midst of the Home Rule Crisis and at the outbreak of the First World War. On the same day, the Suspensory Act 1914 suspended its actual operation.
In 1916, a group of revolutionaries led by the Irish Republican Brotherhood launched the Easter Rising, during which they issued a Proclamation of the Irish Republic. The rebellion was not successful and sixteen of the leaders were executed. The small separatist party Sinn Féin became associated with the Rising in its aftermath as several of those involved in it were party members.
The Irish Convention held between 1917 and 1918 sought to reach agreement on manner in which home rule would be implemented after the war. All Irish parties were invited, but Sinn Féin boycotted the proceedings. By the end of the First World War, a number of moderate unionists came to support Home Rule, believing that it was the only way to keep a united Ireland in the United Kingdom. The Irish Dominion League opposed partition of Ireland into separate southern and northern jurisdictions, while arguing that the whole of Ireland should be granted dominion status with the British Empire.
At the 1918 election Sinn Féin won 73 of the 105 seats; however, there was a strong regional divide, with the Ulster Unionist Party (UUP) winning 23 of the 38 seats in Ulster. Sinn Féin had run on a manifesto of abstaining from the United Kingdom House of Commons, and from 1919 met in Dublin as Dáil Éireann. At its first meeting, the Dáil adopted the Declaration of Independence of the Irish Republic, a claim which it made in respect of the entire island. Supporters of this Declaration fought in the Irish War of Independence.
Two jurisdictions.
During this period, the Government of Ireland Act 1920 repealed the previous 1914 Act, and provided for two separate devolved parliaments in Ireland. It defined Northern Ireland as "the parliamentary counties of Antrim, Armagh, Down, Fermanagh, Londonderry and Tyrone, and the parliamentary boroughs of Belfast and Londonderry" and Southern Ireland "so much of Ireland as is not comprised within the said parliamentary counties and boroughs". Section 3 of this Act provided that the parliaments may be united by identical acts of parliament:
Sinn Féin did not recognise this act, treating elections to the respective parliaments as a single election to the Second Dáil. While the Parliament of Northern Ireland sat from 1921 to 1972, the Parliament of Southern Ireland was suspended after its first meeting was boycotted by the Sinn Féin members, who comprised 124 of its 128 MPs. 
A truce in the War of Independence was called in July 1921, followed by negotiations in London between the government of the United Kingdom and a Sinn Féin delegation. On 6 December 1921, they signed the Anglo-Irish Treaty, which led to the establishment of the Irish Free State the following year, a dominion within the British Empire.
With respect to Northern Ireland, Articles 11 and 12 of the Treaty made special provision for it including as follows:
The Prime Minister of Northern Ireland, Sir James Craig, speaking in the House of Commons of Northern Ireland in October 1922 said that "when 6 December [1922] is passed the month begins in which we will have to make the choice either to vote out or remain within the Free State". He said it was important that that choice be made as soon as possible after 6 December 1922 "in order that it may not go forth to the world that we had the slightest hesitation". On 7 December 1922, the day after the establishment of the Irish Free State, the Houses of the Parliament of Northern Ireland resolved to make the following address to the King so as to exercise the rights conferred on Northern Ireland under Article 12 of the Treaty:
The King received it the following day. These steps cemented Northern Ireland's legal separation from the Irish Free State.
In Irish republican legitimist theory, the Treaty was illegitimate and could not be approved. According to this theory, the Second Dáil did not dissolve and members of the Republican Government remained as the legitimate government of the Irish Republic declared in 1919. Adherents to this theory rejected the legitimacy of both the Irish Free State and Northern Ireland.
The report of Boundary Commission in 1925 established under the Treaty did not lead to any alteration in the border.
Within Northern Ireland, the Nationalist Party was an organisational successor to the Home Rule Movement, and advocated the end of partition. It had a continuous presence in the Northern Ireland Parliament from 1921 to 1972, but was in permanent opposition to the UUP government.
A new Constitution of Ireland was proposed by Éamon de Valera in 1937 and approved by the voters of the Irish Free State (thereafter simply Ireland). Articles 2 and 3 of this Constitution claimed the whole island of Ireland as the national territory, while claiming legal jurisdiction only over the previous territory of the Irish Free State.
Article 15.2 allowed for the "creation or recognition of subordinate legislatures and for the powers and functions of these legislatures", which would have allowed for the continuation of the Parliament of Northern Ireland within a unitary Irish state.
In 1946, Prime Minister Winston Churchill told the Irish High Commissioner to the United Kingdom, "I said a few words in Parliament the other day about your country because I still hope for a United Ireland. You must get those fellows in the north in, though; you can't do it by force. There is not, and never was, any bitterness in my heart towards your country." He later said, "You know I have had many invitations to visit Ulster but I have refused them all. I don't want to go there at all, I would much rather go to southern Ireland. Maybe I'll buy another horse with an entry in the Irish Derby."
Under the Republic of Ireland Act 1948, Ireland declared that the country may officially be described as the Republic of Ireland and that the President of Ireland had the executive authority of the state in its external relations. This was treated by the British Commonwealth as ending Irish membership. In response, the United Kingdom passed the Ireland Act 1949. Section 1(2) of this act affirmed the provision in the Treaty that the position of Ireland remained a matter for the Parliament of Northern Ireland:
Between 1956 and 1962, the IRA engaged in a border campaign against British Army and Royal Ulster Constabulary outposts with the aim of ending British rule in Northern Ireland. This coincided with brief electoral success of Sinn Féin, which won four seats at the 1957 Irish general election. This was its first electoral success since 1927, and it did not win seats in the Republic of Ireland again until 1997. The border campaign was entirely unsuccessful in its aims. In 1957, Prime Minister Harold Macmillan wrote that “I do not think that a United Ireland - with de Valera as a kind of Irish Nehru would do us much good. Let us stand by our friends.”
The Troubles.
The Northern Ireland civil rights movement emerged in 1967 to campaign for civil rights for Catholics in Northern Ireland. Tensions between republican and loyalist groups in the north erupted into outright violence in the late 1960s. The British government deployed troops in the area under Operation Banner. The Provisional Irish Republican Army (IRA) began a thirty-year campaign against British security forces with the aim of winning a united Ireland.
In 1970, the Social Democratic and Labour Party (SDLP) was established to campaign for civil rights and a united Ireland by peaceful, constitutional means. The party rose to be the dominant party representing the nationalist community until the early twenty-first century.
In 1972, the parliament of Northern Ireland was suspended, and under the Northern Ireland Constitution Act 1973, it was formally abolished. Section 1 of the 1973 Act stated, 
A border poll was held in Northern Ireland in 1973. The SDLP and Sinn Féin called for a boycott of the poll. 98.9% of votes cast supported remaining part of the United Kingdom, accounting for 57.5% of the overall electorate.
In 1983, the Irish government led by Taoiseach Garret FitzGerald established the New Ireland Forum as a consultation on a new Ireland. Though all parties in Ireland were invited, the only ones to attend were Fine Gael, Fianna Fáil, the Labour Party and the SDLP. Its report considered three options: a unitary state, i.e., a united Ireland; a federal/confederal state; and joint sovereignty. These options were rejected by Prime Minister Margaret Thatcher. In 1985, the governments of Ireland and of the United Kingdom signed the Anglo-Irish Agreement; the British government accepted an advisory role for the Irish government in the future of Northern Ireland. Article 1 of the Agreement stated that the future constitutional position of Northern Ireland would be a matter for the people of Northern Ireland:
In the Downing Street Declaration, Taoiseach Albert Reynolds and Prime Minister John Major issued a joint statement, in which Major, "reiterated on behalf of the British Government, that they have no selfish strategic or economic interest in Northern Ireland".
Good Friday Agreement.
The Good Friday Agreement in 1998 was a culmination of the peace process. The agreement acknowledged nationalism and unionism as "equally legitimate, political aspirations". In the Northern Ireland Assembly, all members would designate as Unionist, Nationalist, or Other, and certain measures would require cross-community support. The agreement was signed by the governments of Ireland and of the United Kingdom. In Northern Ireland, it was supported by all parties who were in the Northern Ireland Forum with the exception of the Democratic Unionist Party and the UK Unionist Party, and it was supported by all parties in the Oireachtas. It was also opposed by dissident republicans, including Republican Sinn Féin and the 32 County Sovereignty Movement. It was approved in referendums in Northern Ireland and in the Republic of Ireland.
Included in the Agreement were provisions which became part of the Northern Ireland Act 1998 on the form of a future referendum on a united Ireland.
On the establishment of the institutions in 1999, Articles 2 and 3 of the Constitution of Ireland were amended to read:
Response to Brexit.
In a referendum in June 2016 England and Wales voted to leave the European Union. The majority of those voting in Northern Ireland and in Scotland, however, voted for the UK to remain. Of the parties in the Assembly, only the Democratic Unionist Party (DUP), the Traditional Unionist Voice (TUV) and People Before Profit (PBP) had campaigned for a Leave vote. Irish politicians began the discussion regarding possible changes to the border between Northern Ireland and the Republic of Ireland. There are several key issues related to the United Kingdom withdrawal from the European Union, including the establishment of a new external border of the European Union, or the withdrawal of access, to Northern Ireland, of the regional development assistance scheme (and new funding thereof) from the European Union. Sinn Féin cited these concerns as the basis for new discussion on a united Ireland. These calls were rejected by the British government and Unionist politicians, with Theresa Villiers arguing that there was no evidence that opinion in Northern Ireland had shifted towards being in favour of a united Ireland. In the 2017 Assembly election, the DUP lost ten seats and came just one seat ahead of Sinn Féin. Sinn Féin used this opportunity to call for a Northern Ireland referendum on a united Ireland.
The Brexit Secretary, David Davis, confirmed to Mark Durkan, the SDLP MP for Foyle, that in the event of Northern Ireland becoming part of a united Ireland, "Northern Ireland would be in a position of becoming part of an existing EU member state, rather than seeking to join the EU as a new independent state." Enda Kenny pointed to the provisions that allowed East Germany to join the West and the EEC during the reunification of Germany as a precedent. In April 2017 the European Council acknowledged that, in the event of Irish unification, "the entire territory of such a united Ireland would [...] be part of the European Union." The SDLP manifesto for the 2017 UK general election called for a referendum on a united Ireland after the UK withdraws from the EU. However the Secretary of State for Northern Ireland at the time, James Brokenshire, said the conditions for a vote are "not remotely satisfied".
The Brexit withdrawal agreement, signed in October 2019, included a protocol on Northern Ireland; while the north would "de jure" leave the single market, it would still enforce all EU customs rules, while Britain would diverge. This would result in a regulatory "border in the Irish Sea" rather than a border between Northern Ireland and the Republic of Ireland, and caused fears from unionist politicians about Brexit causing a weakening of the UK. In September 2020, the UK government prepared the UK Internal Market Bill, which sought to dis-apply parts of the Northern Ireland protocol despite acknowledging that this broke international law. The bill was rejected by the House of Lords. In December 2020, two weeks before formally leaving the European Single Market, the UK government withdrew some provisions in the section relating to the Northern Ireland protocol. This version of the bill was passed.
Political positions on a united Ireland.
Within the Northern Ireland Assembly, MLAs designate as Unionist, Nationalist or Other. The DUP (28 seats), the UUP (10 seats) the TUV (1 seat) and the Independent MLA Claire Sugden are designated as Unionist; Sinn Féin (which won 27 seats in the 2017 Assembly election) and the SDLP (12 seats) are designated as Nationalist; the Alliance Party (8 seats), the Green Party (2 seats) and the PBP (1 seat) are designated as Other.
There are a number of minor nationalist parties, including the Irish Republican Socialist Party, which supports a united socialist Irish state and is affiliated with the Irish National Liberation Army. Another such party, Republican Sinn Féin, linked to the Continuity IRA, maintain the Irish republican legitimist theory that neither state in Ireland is legitimate. Its "Éire Nua" (in English, "New Ireland") policy advocates a unified federal state with regional governments for the four provinces and the national capital in Athlone. None of these parties has significant electoral support.
Within the Oireachtas, there has traditionally been broad support for a united Ireland, with differences over the twentieth century on how it would be achieved. This includes Sinn Féin, which has had seats in the Dáil since 1997. The initial party constitution of Fianna Fáil in 1926 under Éamon de Valera included as the first of its aims, "To secure the Unity and Independence of Ireland as a Republic". In 1937, de Valera proposed the Constitution of Ireland which laid claim to the whole island of Ireland. In the 1980s, led by Charles Haughey, the party opposed the consideration of options other than a unitary state in the New Ireland Forum Report and opposed the Anglo-Irish Agreement; this stance led in part to the Des O'Malley and Mary Harney leaving Fianna Fáil and establishing the Progressive Democrats, a party that lasted from 1985 to 2008. Fianna Fáil leaders Albert Reynolds and Bertie Ahern led Irish governments in favour of the Downing Street Declaration and the Good Friday Agreement respectively.
When formed in 1933, Fine Gael initially used the subtitle "United Ireland". Fine Gael leader Garret FitzGerald convened the New Ireland Forum in 1983 and negotiated the Anglo-Irish Agreement. In the aftermath of the vote on Brexit, Enda Kenny sought assurances on the position of Northern Ireland in the case of a united Ireland. The Irish Labour Party has adopted a similar approach to Fine Gael in government to a united Ireland.
In a survey of TDs conducted by "TheJournal.ie" on support for a border poll and a united Ireland conducted in December 2016, only TDs from the Anti-Austerity Alliance (now Solidarity) stated they were opposed to a united Ireland at the present moment.
Of the British parties, the Conservative Party is explicitly unionist; it has formally been called the "Conservative and Unionist Party" since a merger with the Liberal Unionist Party in 1912. The UUP was affiliated with the National Union of Conservative and Unionist Associations until 1985. The Northern Ireland Conservatives are a minor unionist party in Northern Ireland.
Historically, there has been support for a united Ireland within the left of the British Labour Party, and in the 1980s it became official policy to support a united Ireland by consent. The policy of "unity by consent" continued into the 1990s, eventually being replaced by a policy of neutrality in line with the Downing Street Declaration. The former Labour leader Jeremy Corbyn supports a united Ireland, although he has said that it is "up for the Irish people to decide" whether to remain part of the UK. They do not organise electorally in Northern Ireland, respecting the SDLP as their sister party within the Party of European Socialists. Similarly, the Liberal Democrats co-operate with the Alliance Party and share their support of the Good Friday Agreement while expressing reservations about what they perceive as ‘institutionalised sectarianism’ in the agreement. Former Alliance leader Lord Alderdice is a member of the Liberal Democrats in the House of Lords.
Opinion polling.
The Good Friday Agreement states that "the Secretary of State" should call a referendum "if at any time it appears likely to him that a majority of those voting would express a wish that Northern Ireland should cease to be part of the United Kingdom and form part of a united Ireland."
Public opinion.
Northern Ireland.
Historically, opinion polls of the Northern Ireland population consistently showed majorities opposed to a United Ireland and in support of Northern Ireland remaining part of the United Kingdom. For example, in a November 2015 survey by RTÉ and the BBC, 30% of the population expressed support for a United Ireland in their lifetime with 43% opposed and 27% undecided. However, when asked about the status of Northern Ireland in the short-to-medium term, support for unity was lower at around 13% of the population. The 2013 annual Northern Ireland Life and Times survey conducted by the Queen's University Belfast and Ulster University found that a united Ireland was the favoured long term option of 15% of the population while remaining part of the United Kingdom was the favoured long term option of 66% of the population. When the same survey was carried out in 2015, support was 22%.
In 1973, the population of Northern Ireland was granted a referendum on whether Northern Ireland should remain part of the United Kingdom or join with the Republic of Ireland to form a united Ireland. The result was 98.9% in favour of union with the rest of the UK, but the poll was overwhelmingly boycotted by nationalists, and the turnout was therefore 58.7%. The pro-UK vote did however represent 57.5% of the entire electorate, notwithstanding the boycott. Provisions for future referendums were included in the Good Friday Agreement and the Northern Ireland Act 1998.
Many Unionist Protestants in Northern Ireland argue they have a distinct identity that would be overwhelmed in a united Ireland. They cite the decline of the small Protestant population of the Republic of Ireland since independence from the United Kingdom, the economic cost of unification, their place in a key international player within the UK and their mainly non-Irish ancestry. Unionist people in Northern Ireland primarily find their cultural and ethnic identity from the Scottish and English planters (colonists), whose descendants can be found in the three counties of Ulster which are governed by the Republic of Ireland. Such individuals celebrate their Scots heritage each year like their counterparts in the other six counties. While Catholics in general consider themselves to be Irish, Protestants generally see themselves as British, as shown by several studies and surveys performed between 1971 and 2006. Many Protestants do not consider themselves as primarily Irish, as many Irish nationalists do, but rather within the context of an Ulster or British identity. A 1999 survey showed that a little over half of Protestants felt "Not at all Irish", while the rest "felt Irish" in varying degrees.
A 2011 survey by Northern Ireland Life and Times found that 52% of Northern Irish Catholic respondents favoured union with Great Britain over a united Ireland. This is despite the fact that most Catholics who vote do so for political parties that are Nationalist.
According to a 2015 opinion poll, 70% expressed a long-term preference of the maintenance of Northern Ireland's membership of the United Kingdom (either directly ruled or with devolved government), while 14% express a preference for membership of a united Ireland. This discrepancy can be explained by the overwhelming preference among Protestants to remain a part of the UK (93%), while Catholic preferences are spread across a number of solutions to the constitutional question including remaining a part of the UK (47%), a united Ireland (32%), Northern Ireland becoming an independent state (4%), and those who "don't know" (16%).
Since the 2016 Brexit vote, support for reunification has increased, with 22% of respondents favourable towards reunification, up from 17% in 2013. 43% of Catholics would now back reunification, up from 35% in 2013. According to this survey, support for a referendum stands at 53% of Catholic respondents, compared to 28% of Protestant respondents.
A poll in May 2017 found that 51% were in favour of holding a referendum on a united Ireland within the next five years.
In October 2017 a poll found that 62 percent were in favour of having a referendum on a united Ireland within the next ten years. The same poll found that 55 percent of those asked would vote to remain within the United Kingdom if a referendum was held tomorrow while 34 percent said they would vote yes and 10 percent were undecided. The poll also asked how those asked would vote in the event of a "hard Brexit" that was bad for Northern Ireland and a "soft Brexit" that was good for Northern Ireland but the undecided were excluded. In the event of the latter 62.84 percent would vote to remain in the UK while 37.14 would vote for a United Ireland. In the case of the former 53.57 percent said they would vote to remain in the United Kingdom while 46.43 would vote to leave it and have a United Ireland.
In December 2017, an opinion poll carried out by LucidTalk on more than 2,000 people saw 48% of respondents willing to vote for a united Ireland if a border poll was held in the event of a hard Brexit, against 45% for maintaining the status quo. 6% of respondents were undecided, and less than 1% of respondents stated that they would not vote.
A Lord Ashcroft poll, with 1,542 people questioned online from 30 August to 2 September 2019, found 46% of the respondents would vote for leaving the Union and joining the Republic of Ireland, and 45% would vote to stay in the UK. The other respondents would not vote or didn't know.
Assorted opinion polls.
An opinion poll of 1,089 people conducted by LucidTalk in 2014 around the time of the Scottish referendum posed several questions. On the question of whether or not there should be a border poll, 47% said "yes", 37% "no" and 16% "don't know". On the question, "If a referendum on Irish Unity was called under the Good Friday Agreement would you vote: Yes for unity as soon as possible, Yes for unity in 20 years, or No for Northern Ireland to remain as it is", the results were as follows.
In 2016 an Ipsos MORI poll asked "If there was a referendum on the border tomorrow would you:" and the answers for different regions of Northern Ireland were as follows,
The same poll recorded answers from people in different age groups as follows,
Answers from people of different religious backgrounds were as follows,
A similar LucidTalk poll conducted in May 2017 found that 51% of people would be in favour of a border poll within the next five years while 39% would not and 10% did not know. Respondents were not asked how they would vote in such a poll.
A LucidTalk opinion poll of 1,334 Northern Irish residents conducted in Oct–Nov 2018 found majority support (60%) for Northern Ireland remaining in the United Kingdom if the UK were to remain an EU member state, an even split (48% each) if the UK were to leave the EU on the terms negotiated between the British Government and the EU, and majority support (55%) for Northern Ireland unifying with the Irish republic if the UK left the EU under a no-deal scenario.
In the Republic of Ireland.
There are some very small pressure groups in the Republic of Ireland, such as the Reform Group and lodges of the Orange Order, that are sympathetic to Northern Ireland remaining within the United Kingdom for the foreseeable future, but their impact on the broader political opinion is negligible. A minority of politically conservative Catholic writers from the Republic of Ireland, such as Mary Kenny and Desmond Fennell have expressed misgivings about a united Ireland, fearing the incorporation of a large number of Protestants would threaten what they see as the Catholic nature of the Republic. A Red C/Sunday Times poll in 2010 found that 57% are in favour of a united Ireland, 22% say they are opposed, while 21% are undecided.
In October 2015 an opinion poll commissioned by RTÉ and the BBC and carried out by Behaviour & Attitudes asked those in the Republic of Ireland the question "There are a number of possible options for the constitutional status of Northern Ireland. In the short to medium term, do you think Northern Ireland should…" with the following responses,
The same poll also asked "Thinking of the long-term policy for Northern Ireland, would you like to see a united Ireland in your lifetime?" with the following responses,
The poll then asked a further question concerning the influence of the tax consequences of a united Ireland on support for it,
In December 2016 RTÉ's Claire Byrne Live/ Amárach Research panel asked 'Is it time for a united Ireland?' Forty-six percent of those asked said yes while 32% said no and 22% said that they didn't know. Support was highest among those aged 25–34 with 54% saying yes.
In May 2019 an RTÉ/REDC exit poll at the 2019 elections found that 65% of respondents are in favour of a united Ireland, whereas 19% were against it.
In Great Britain.
A 2019 poll by Ipsos Mori and King's College London asked people in Britain (England, Scotland, and Wales): "If there were to be a referendum in Northern Ireland on its future, would you personally prefer Northern Ireland to choose to stay in the UK or leave the UK and join the Republic of Ireland?" The responses revealed that 36% wanted Northern Ireland to stay in the UK, 19% wanted it to join the Republic, 36% had no preference, and 9% were undecided. It further revealed that support for Northern Ireland remaining in the UK was highest among those who intended to vote Conservative (49%) compared to 35% for Labour voters and 31% for Liberal Democrat voters.