Pan-democrats failed for a third time yesterday to gain backing for a Legco inquiry into the chief executive's acceptance of tycoons' favours.
But now they plan to aim higher and seek his impeachment.
After a five-hour debate yesterday, lawmakers defeated a motion to invoke Legco's special powers to investigate Donald Tsang Yam-kuen.
The motion was launched by Lee Wing-tat, of the Democratic Party, and Cyd Ho Sau-lan, of the Labour Party. After the vote, Labour members said they would discuss the next move with fellow pan-democrats.
Non-affiliated legislator Paul Tse Wai-chun, who has long called for a motion of impeachment, said he still supported the effort.
'An impeachment is actually the most appropriate thing to do towards a chief executive who has been found with so many problems.
'The public feel strongly towards the matter, and as responsible legislators we should respond to the anger. I sincerely hope that pan-democrats will support me on the motion [for impeachment].'
Launching the impeachment procedure will require the support of at least 15 legislators.
The pan-democrats had wanted a probe into Tsang's acceptance of trips on private planes and yachts offered by his tycoon friends.
They also questioned his initial plan - now abandoned - to rent a penthouse in Shenzhen from a pro-Beijing businessman who is a major investor in a digital radio station. An ICAC inquiry is under way and Tsang has set up a panel to review the code of conduct for senior officials, including the chief executive.
Lee argued: 'The ICAC investigation will take a long time and has a high threshold before prosecution [can take place].
'It will not let the public know about the content [of its findings]. The integrity of a chief executive is a matter of public interest and the legislature is responsible for pushing ahead with the matter to find out what happened.'
Non-affiliated legislator Paul Chan Mo-po said: 'The present situation gives the public the impression that the chief executive can be above the law.'
But Yip Kwok-him, of the Democratic Alliance for the Betterment and Progress of Hong Kong, said: 'The ICAC has started a probe. We feel it is necessary to respect the commission and let it run an investigation first.'
After the defeat, Lee said: 'It will not be the end of the issue. People will continue to demand answers from the chief executive.'