Rafael Hui Si-yan is tipped to quit the post of chief secretary by the end of next year to assist Donald Tsang Yam-kuen in the chief executive election in 2007.
Sources close to Mr Hui said he had hinted to friends that his second stint in the government would be shorter than the two-year term of the Tsang administration because of Mr Tsang's re-election bid.
Mr Hui quit the government to head the Mandatory Provident Fund Authority in 2000, and then became semi-retired in 2002.
Although the next election is scheduled for early 2007, pundits say the pre-election canvassing will heat up during the election of the new Election Committee around the end of next year.
As in the last chief executive election, Mr Hui is expected to play a key role in Mr Tsang's campaign. This is also thought to be one of the reasons why he has decided not to make his move into the chief secretary's official residence at Victoria House.
He has maintained privately that he has no plan to stay in the post-2007 administration.
