Nick Clegg made a last-minute effort to boost his party's ailing prospects in the Oldham East and Saddleworth by-election yesterday, making a third trip to boost morale ahead of tomorrow's ballot.
Two polls taken over the weekend suggest Labour is 17 points ahead of the Liberal Democrat candidate, Elwyn Watkins.
However, Liberal Democrat aides claimed last night they had closed the gap by taking votes from the Tories. They pointed to another poll indicating a one-point lead for Labour and a collapse in support for the Tories.
"That is much more the way it feels on the ground," said one party source. "We are taking votes from the Tories, there is an anti-Labour vote and people also like Elwyn as a good local candidate."
A resounding defeat for the Liberal Democrats would set nerves jangling within the party, suggesting it will be punished for forming a Government with David Cameron and the Tories. Mr Watkins lost by just 103 votes at the election.
Speaking during his brief visit, Mr Clegg refused to accept his party was heading for a heavy defeat.
"We have knocked on 35,000 doorsteps and we believe it is going to be pretty close," he said. "We are really in this contest.
"This is a two-horse race. The only way to stop a Labour victory they don't deserve is to rally behind Elwyn."
The contest, called when the former Labour MP, Phil Woolas, was removed after making false statements against Mr Watkins at the general election last May, has again become bad tempered.
The Liberal Democrats and Labour have attacked each other for using underhand tactics. The Liberal Democrats have been accused of breaking election rules by announcing a Government policy during the by-election.
However, Labour has been accused of spreading "misinformation" about police cuts and health centre closures, as well as being dishonest about the local credentials of their candidate, Debbie Abrahams.