The race for mayor of London appeared to have narrowed to a straight fight between Ken Livingstone and Steven Norris last night after a new poll put Frank Dobson, Labour's candidate, firmly in third place.
The ICM poll for the London Evening Standard put Mr Livingstone, the independent, on 51 per cent, Mr Norris, the Tory candidate, on 17 per cent and Mr Dobson on 14.
With Susan Kramer, the Liberal Democrat, closely behind on 12 per cent, Labour faces the humiliating prospect that its candidate may even come fourth when the result is announced on 5 May.
Worse still for Tony Blair, the ICM survey showed for the first time that Mr Dobson's unpopularity was affecting the party's ratings, and raised the prospect of London Labour MPs losing seats at the next general election.
ICM's poll of a sample of 1,004 London voters found that Mr Livingstone had strengthened his position as front-runner, with his rating up 2 percentage points from ICM's last survey two weeks ago.
The former GLC leader now looks unstoppable as the people's choice for the role of Britain's first directly elected mayor.
At the same time, Mr Norris picked up one point and Mr Dobson slipped one point, increasing the gap between them. The results for Mr Dobson are even worse among those certain to vote, where he is level with Mrs Kramer on 12 per cent.
The survey will come as a bitter blow to the Dobson camp as it had hoped that Mr Blair's high-profile support for his candidate, with repeated attacks on "the cost of Ken", would help close the gap.
But as polls for the London elections opened yesterday - part of an experiment in early voting ahead of the main election date of May 4 - the ICM poll made depressing reading for the Prime Minister. It shows that Labour's support for the next general election has slipped by five points, a drop that would cost the Goverment several seats.
The party's support for the list section of the Greater London Assembly has also fallen and it is projected to win just 11 of the 25 sets available.
Mr Livingstone said the poll was now a battle between himself and Mr Norris, with the modernisation of the London Underground the key issue.
"The latest opinion poll makes clear that voters will have a straight choice between my proposal for a safe, modernised Tube system within the public sector, or Steve Norris's alternative of a completely privatised Underground," he said.
Mr Norris agreed that the mayoral election had narrowed to a two-way contest. "With a week to go, London now has a clear choice - Norris or Livingstone, action or politics, a better Tube as against political dogma," he said.
Mr Dobson insisted that the new poll bore no resemblance to Labour's canvassing returns which, he said, showed support "flowing away" from Mr Livingstone.
Ms Kramer said she was "confident" that she would finish ahead of Mr Dobson and even claimed she could overhaul Mr Norris as well, to pose the only realistic challenge to Mr Livingstone.