ates, but a multitude of lesser parties exist with varying degrees of influence, and sometimes these lesser parties are able to elect officials who participate in the legislature. A report in the Christian Science Monitor, for example, suggested that Spain was moving towards a "greater two-party system" while acknowledging that Spain has "many small parties." In political systems based on the Westminster system, which is a particular style of parliamentary democracy based on the British model and found in many commonwealth countries, a majority party will form the government and the minority party will form the opposition, and coalitions of lesser parties are possible; in the rare circumstance in which neither party is the majority, a hung parliament arises. Sometimes these systems are described as two-party systems but they are usually referred to as multi-party systems. There is not always a sharp boundary between a two-party system and a multi-party system.
Generally, a two-party system becomes a dichotomous division of the political spectrum with an ostensibly right-wing and left-wing party: the Nationalist Party vs. the Labour Party in Malta, Liberal vs. Labor in Australia, Republicans vs. Democrats in the United States and the Conservative Party vs. the Labour Party in the United Kingdom.
Other parties in these countries may have seen candidates elected to local or subnational office, however. Historian John Hicks claims that the United States has never possessed for any considerable period of time the two party system in its pure and undefiled form.
In some governments, certain chambers may resemble a two-party system and others a multi-party system. For example, the politics of Australia are largely two-party (if the Liberal Party and National Party are considered the same party at a national level due to their long-standing alliance) for the Australian House of Representatives, which is elected by Instant Runoff Voting, (known within Australia as preferential voting). However, third parties are more common in the Australian Senate, which uses a proportional voting system more amenable to minor parties.
India too is showing characteristics of two party system with United Progressive Alliance (UPA) and National Democratic Alliance (NDA) as the two main players. It is to be noted that both UPA and NDA are not two political parties but alliances of several smaller parties. Other smaller parties not aligned with either NDA or UPA exist, and overall command about 20% of the 2009 seats in the Lok Sabha.
Malta are somewhat unusual in that while the electoral system is single transferable vote (STV), traditionally associated with proportional representation, minor parties have not earned much success. No third parties won any seats in the Parliament in Malta's most recent election, for example. The Labour Party and the Nationalist Party are the dominant parties.
Comparisons with other party systems
Two-party systems can be compared with:
- Multi-party systems. In these, the effective number of parties is greater than two but usually fewer than five; in a two-party system, the effective number of parties is two (according to one analysis, the actual average number of parties varies between 1.7 and 2.1.) The parties in a multi-party system can control government separately or as a coalition; in a two-party system, however, coalition governments rarely form. Examples of nations with multi-party systems include Brazil, Canada, Denmark, Finland, France, Germany, India, Pakistan, Indonesia, Ireland, Israel, Italy, Mexico, Nepal, the Netherlands, New Zealand, Norway, Portugal, Spain, Sweden, Taiwan, and the United Kingdom.
- Single-party systems or dominant-party systems happen in nations where no more than one party is codified in law and/or officially recognized, or where alternate parties are restricted by the dominant party which wields power. Examples include rule by the Communist Party of China and the People's Action Party of Singapore.
There are several reasons why, in some systems, two major parties dominate the politi