Hong Kong's No. 2 government official said Thursday that she was resigning to prepare for a leadership bid for the southern Chinese city's top job.
Chief Secretary Carrie Lam said she tendered her resignation to Chief Executive Leung Chun-ying and asked him to submit it to Beijing for approval.
Lam, 59, is the third person to announce plans to join the contest for the job of leading the former British colony, the scene of increasingly bitter political divisions between pro-democracy activists and Beijing loyalists.
"There's only one reason for me to resign at this juncture and that is, if my resignation is approved by the central people's government, I intend to prepare to contest in the upcoming chief executive election," Lam said she wrote in her letter.
Current leader Leung is deeply unpopular and announced last month that he won't seek another term, citing family reasons. His five-year term, which ends in June, was marked by 11-week pro-democracy "Umbrella Movement" protests in 2014 against Beijing's plan to restrict electoral reforms.
Lam, who said she would go on leave starting Friday, has been nicknamed the "good fighter" because of her reputation for being pragmatic and effective; she was Leung's pick to negotiate with student protests leaders two years ago.
Another potential contender, Finance Secretary John Tsang, quit last month but Beijing has yet to approve his resignation and he hasn't yet officially announced he will run.
Hong Kong leaders are chosen by a 1,200-member panel of mostly pro-Beijing tycoons and elites, which is scheduled to make its pick in March. So far, retired judge Woo Kwok-hing and lawmaker Regina Ip have publicly declared their intention to run for the job of leading the city of 7.2 million.