The left-wing MP had hoped to achieve unstoppable momentum by winning scores of nominations from constituency parties in the capital. He would almost certainly have won more support than his rivals, making it harder for Tony Blair to halt his bandwagon.
But tomorrow leaders of the London Labour Party will foil Mr Livingstone's plans by agreeing that no nominations will be needed or collected. It will propose a system of self-nomination, under which any party member can put him or herself forward without the backing of a constituency or trade union.
Officially, the reason for the change is to allow more women and ethnic minority candidates to enter the race to become Labour's candidate. Privately, senior Labour figures admit the move is also aimed at stopping a "Livingstone bandwagon" in its tracks.
Left-wingers warned yesterday there would be "uproar" over the move, saying it flew in the face of the London party's annual conference this year, which agreed that anyone proposed by 10 constituency parties would automatically enter the ballot of London Labour members to choose the party's candidate for mayor.
Mr Livingstone warned the plan to block him could backfire on Labour when Londoners voted in the election for mayor. "There would be such division inside the Labour Party we would not get people out working and we would lose it to the Tories," he said.
The proposed rules will make it easier for the Labour leadership to block Mr Livingstone when a selection panel drawn from the National Executive Committee and the London party interviews candidates early next year.
The Brent East MP is widely expected to be vetoed, with the panel refusing to allow his name on to the list of four or five names who will enter the ballot of London party members to choose the candidate.
The panel is expected to cite Mr Livingstone's past "disloyalty" to the party leadership as evidence that he would be unsuitable to carry Labour's banner in the race for mayor.
Labour officials are said to be poring over the MP's speeches and newspaper articles, including the column he writes for The Independent, as they gather evidence against him. "Downing Street is in a panic," one minister admitted. "It seems to have woken up to the problem very late in the day. It's the usual crisis management."
Attacking Labour's headquarters, Mr Livingstone warned that London party members would be watching to see whether their official policy would be overturned "at the behest of a few control freaks in the Millbank Tendency".
But Labour officials insisted the proposal for a selection panel was coming from the regional board of the London party, on which Blair loyalists enjoy a majority of about 3-1.
Other possible Labour candidates include Pauline Green, leader of the Socialist group in the European Parliament; Glenda Jackson, the Transport minister; Tony Banks, the Sports minister; Trevor Phillips, the broadcaster and Lord Harris, the former leader of Haringey Council.
Mr Blair's attempts to avoid a setback over who succeeds Ron Davies as Labour leader in Wales will step up a gear today when the party's Welsh executive interviews the candidates. It will appeal to Rhodri Morgan, the maverick MP opposed by Mr Blair, to stand down in favour of Alun Michael, the Welsh Secretary, backed by the Prime Minister, in order to avoid a divisive election contest.
Mr Morgan said yesterday he did not object to a meeting to resolve the issue in the party's interests, but added: "If `unity' is a code for Alun Michael's candidacy, it's no dice. If they are misusing and abusing the word to mean that Alun Michael must be given a clear run, it's completely preposterous."Reuse content