On 12 January 2017, Carrie Lam resigned from her Chief Secretary post (having at some point previously renounced her British citizenship, which would have excluded her from running) and announced her plan to run for Chief Executive if her resignation was approved.
In a closed-door meeting, she laid out an eight-point "achievable new vision" for Hong Kong and told participants that God had called on her to run.
On 16 January, the two Secretaries' resignations were simultaneously approved by the central government.
Some pro-Beijing politicians saw this as a sign that Lam was the central government's favoured candidate, as Tsang had resigned a full month before Lam.
Lam officially declared her candidacy on the same day, promising good governance with greater transparency and "new blood" in her cabinet, at a press conference in which she was joined by Executive Councillor Bernard Chan, director of her campaign office.
The chairman's council of her campaign office included prominent figures, former Hong Kong Stock Exchange chairman Ronald Arculli among them.

As Lam declared her candidacy and Tsang was expected to run, political analysts observed that Regina Ip's chances of getting the minimum 150 nominations were reduced.
Ip revealed that two or three electors, including Allan Zeman, had turned their backs on her to support Lam.
A teary-eyed Ip told a media gathering on 17 January, "[i]n the past ten years I started from nothing, working hard bit by bit, splashing out my own money, putting in much mental and physical effort.
Can you say I had not taken on responsibilities for Hong Kong society?
When I handled Article 23, I did not perform satisfactorily?"
 Ip's remarks came after Leung Chun-ying praised Lam for her "ability and willingness to take on responsibility".

John Tsang officially declared his candidacy on 19 January with a slogan of "Trust, Unity, Hope", after more than a month-long delay in the acceptance of his resignation by the central government, which put his campaign in limbo.
To contrast himself with Lam, who was perceived to follow Leung Chun-ying's hardline and divisive policies, Tsang described himself as a good listener accepting of different views.
He appealed to "all 7.35 million Hongkongers so that together we can make Hong Kong a better place."
Retired senior civil servant former Permanent Secretary for the Civil Service Rebecca Lai Ko Wing-yee and former Permanent Secretary for Food and Health Sandra Lee Suk-yee became director and officer of Tsang's campaign office respectively, despite a number of his supporters switching to Lam's camp amid reports suggesting he failed to get endorsement from Beijing.
Tsang also launched his election Facebook page, which drew more than 100,000 likes in a day.

In a closed-door meeting with senior media executives on 20 January, Lam reportedly said she decided to run to prevent the election from being won by someone not accepted by Beijing, which would cause "constitutional crisis".
Woo Kwok-hing criticised Lam for using a "despicable tactic" to attack her opponents.
Lam's campaign office later clarified that Lam was only making a general comment without targeting anybody in particular.
She was also criticised for being out of touch with ordinary people after she appeared unfamiliar with how to use an Octopus card to pass through a turnstile in the Mass Transit Railway (MTR).
A similar gaffe followed shortly thereafter when it was reported that Lam did not know convenience stores do not sell toilet paper and had to take a cab back to her former official residence to get one, which was dubbed "loo paper-gate" by English media.
She was further under criticism for being ignorant after giving HK$500 to an illegal beggar who was allegedly "trafficked" from China.
On 12 January 2017, Carrie Lam resigned from her Chief Secretary post (having at some point previously renounced her British citizenship, which would have excluded her from running) and announced her plan to run for Chief Executive if her resignation was approved. In a closed-door meeting, she laid out an eight-point "achievable new vision" for Hong Kong and told participants that God had called on her to run. On 16 January, the two Secretaries' resignations were simultaneously approved by the central government. Some pro-Beijing politicians saw this as a sign that Lam was the central government's favoured candidate, as Tsang had resigned a full month before Lam. Lam officially declared her candidacy on the same day, promising good governance with greater transparency and "new blood" in her cabinet, at a press conference in which she was joined by Executive Councillor Bernard Chan, director of her campaign office. The chairman's council of her campaign office included prominent figures, former Hong Kong Stock Exchange chairman Ronald Arculli among them.
As Lam declared her candidacy and Tsang was expected to run, political analysts observed that Regina Ip's chances of getting the minimum 150 nominations were reduced. Ip revealed that two or three electors, including Allan Zeman, had turned their backs on her to support Lam. A teary-eyed Ip told a media gathering on 17 January, "[i]n the past ten years I started from nothing, working hard bit by bit, splashing out my own money, putting in much mental and physical effort. Can you say I had not taken on responsibilities for Hong Kong society? When I handled Article 23, I did not perform satisfactorily?"  Ip's remarks came after Leung Chun-ying praised Lam for her "ability and willingness to take on responsibility".
John Tsang officially declared his candidacy on 19 January with a slogan of "Trust, Unity, Hope", after more than a month-long delay in the acceptance of his resignation by the central government, which put his campaign in limbo. To contrast himself with Lam, who was perceived to follow Leung Chun-ying's hardline and divisive policies, Tsang described himself as a good listener accepting of different views. He appealed to "all 7.35 million Hongkongers so that together we can make Hong Kong a better place." Retired senior civil servant former Permanent Secretary for the Civil Service Rebecca Lai Ko Wing-yee and former Permanent Secretary for Food and Health Sandra Lee Suk-yee became director and officer of Tsang's campaign office respectively, despite a number of his supporters switching to Lam's camp amid reports suggesting he failed to get endorsement from Beijing. Tsang also launched his election Facebook page, which drew more than 100,000 likes in a day.
In a closed-door meeting with senior media executives on 20 January, Lam reportedly said she decided to run to prevent the election from being won by someone not accepted by Beijing, which would cause "constitutional crisis". Woo Kwok-hing criticised Lam for using a "despicable tactic" to attack her opponents. Lam's campaign office later clarified that Lam was only making a general comment without targeting anybody in particular. She was also criticised for being out of touch with ordinary people after she appeared unfamiliar with how to use an Octopus card to pass through a turnstile in the Mass Transit Railway (MTR). A similar gaffe followed shortly thereafter when it was reported that Lam did not know convenience stores do not sell toilet paper and had to take a cab back to her former official residence to get one, which was dubbed "loo paper-gate" by English media. She was further under criticism for being ignorant after giving HK$500 to an illegal beggar who was allegedly "trafficked" from China.
2017 Hong Kong Chief Executive election