But as senior officials in his Kensington and Chelsea seat met to begin choosing a replacement, some whose names had been mentioned were ruling themselves out.
Among those who have confirmed that they are interested in replacing Sir Nicholas are the former defence minister Alan Clark and MP Terry Dicks.
Other MPs who are expected to take part in the contest for one of the Conservatives' safest seats are the Northern Ireland minister Sir John Wheeler and the Shoreham MP Michael Stephen, both of whose seats have been affected by boundary changes.
Two other names were being mentioned last night as possible contenders. They were Martin Howe, Euro-sceptic nephew of the former foreign secretary Sir Geoffrey, and Joan Hanham, leader of Kensington and Chelsea borough council.
Last week the association refused to endorse Sir Nicholas's continued candidacy after he was found face-down on a pavement after a drinks party at this year's Conservative conference in Bournemouth. It is moving quickly to replace him, with a closing date for applications on 3 January.
More outlandish suggestions on the future of the seat include speculation that it was being "kept warm" by Sir Nicholas for Chris Patten, who will return from his post as governor of Hong Kong next year. An alternative version suggests that the party might support Joan Hanham on condition that she steps down after one term to make way for Michael Forsyth, Secretary of State for Scotland, who is expected to lose his seat at the general election.
Among those who were thought less likely to stand was Hartley Booth, MP, who succeeded Margaret Thatcher in Finchley and who lost his junior ministerial post after a liaison with a researcher.
One friend of Mr Booth said last night that although his seat had also been hit by boundary changes, he would be more likely to seek a new one outside London because the media in the capital would be more likely to keep raking up his past.
Andrew Dalton, chairman of the Kensington and Chelsea party, had also been mentioned as a strong contender for the post. Last night he said he had been pressed hard to stand by both officials and members of the association, but had finally decided not to do so.
"I have come to the conclusion that flattering though that might be and much as I might want to do it, I think for the sake of the integrity of the process and myself this is not one to do," he said.
Mr Dalton said the party was willing to consider candidates who were not on Conservative Central Office's approved list of candidates. It would certainly be happy to meet local party members who were interested or possibly "people of achievement" from elsewhere. He suggested someone prominent in the world of business might be an appropriate candidate.Reuse content