The claim followed statements from Labour sources who said this week that up to a dozen Tories were actively talking to them about the possibility of a Tory split if William Hague was elected leader of the party. Alastair Campbell, the Prime Minister's press secretary, said the party had a number of links, both informal and formal, with Tory MPs.
Miss Nicholson said "lots" of Tories, some of them MPs, had approached her. Many of them had been deeply distressed by the party's plight, she added.
"Lots of people from inside and outside Parliament have been talking to me. Individuals of prominent position and of humble position have talked to me almost every day. Some people have already decided what they are going to do," she said.
Although a significant group of MPs might be thinking of joining the Liberal Democrats, the decision was very hard for them, she added. "It's difficult to leave the party that you pledged yourself to. It's rather like the end of a marriage."
Miss Nicholson would not say how many MPs had told her that they were thinking of jumping ship, but she said she did not believe the party could survive in its current form. "I don't think the Conservative Party is able to be led any longer. I personally believe we are seeing its extinction in the shape and form it has been in this century ... I believe it will become a true right-wing party," she said.
Members of Kenneth Clarke's camp believe the rumours of a split have been put about to destabilise their chances of success in the Conservative leadership contest. However, with both Labour and the Liberal Democrats claiming that they had been talking to Tory dissidents, a split seemed increasingly likely. The claims were dismissed by sources on the left of the Conservative Party, though. They said there was "practically none of that kind of talk".Reuse content