The Brent East MP, Mr Ken Livingstone, will meet the Deputy Prime Minister, Mr John Prescott, this afternoon amid growing speculation that the former will not stand as an independent candidate for the post of London mayor.
Mr Livingstone has come under increasing pressure in recent days not to stand against Labour's official candidate, Mr Frank Dobson. Running against the former health secretary would lead to Mr Livingstone's expulsion from the Labour Party and he would therefore risk permanent irrelevance were he to lose the contest.
Mr Livingstone was beaten to the candidacy by Mr Dobson thanks to a collegiate voting system which was described by the veteran left-wing MP, Mr Tony Benn, as "a fiddle". Opinion polls suggest that Mr Livingstone is far more popular with London's voting population than any of the other contenders.
Speaking on the BBC's Panorama programme to be broadcast this evening, Mr Livingstone says that he is facing "the most difficult decision of my life".
He also warns that if Labour's continuing infighting over the mayoral race is not resolved it could blow up in the party's face.
"You've got the sort of anger there has been in Wales, and if between No 10 and myself we can't find a way of sorting this out ... then I think we are going to be punished on May 4th at the ballot box."
Mr Livingstone also admits that among many of his close friends and left-wing colleagues in parliament there is strong opposition to his standing, and many feel that he should stay and fight his corner from within the party.
Last week his own constituency association lent its support to his staying in Labour, and it is reported that his partner of 18 years, Amnesty International's UK Director, Ms Kate Allen, is also opposed to his standing as an independent.
Today's meeting will most likely be used to arrange a deal which would allow Mr Livingstone to stand down while also saving face. His opposition to the public-private partnership in the funding of London's underground network will be the key issue.
Any resulting change in the government's handling of the Tube would be regarded as a major victory for Mr Livingstone, and it is also believed that he may be offered a ministerial post in return for standing down.
One senior Labour official was quoted in yesterday's Sunday Telegraph as saying: "He cannot become chancellor, but anything reasonable he wants will be his. We think he is now accepting the situation which is that we will slaughter him if he stands. There is a deal on the table and he would be wise to accept it."