Campaigners were increasingly weighing up the prospect of a shock Ukip victory in Eastleigh this morning, as candidates took to the streets for the last day of campaigning before the polls open.
Bookmakers William Hill dropped the odds on a Ukip victory from 25-1 to 8-1 this week, then cut them even further through the course of today until they reached 5-1. The party started with odds of 100/1 at the start of the campaign.
"This is set to be the biggest betting by-election we've ever seen with a six figure industry turnover assured," Hill spokesman Graham Sharpe said.
"There has been susbtantial support for all three of the front runners, with Ukip coming through strongly as the finishing post looms up."
Influential Conservative backbencher David Davis openly weighed up the possibility of a m ajor upset when the constituency goes to the polls tomorrow.
"I think if we came third it would be a crisis, I think that’s the case, and if it’s a close second with Ukip on our tail it will also be uncomfortable," he said.
"Let's be clear, it's not going to dislodge David Cameron, he’s going to be there till the next election, but the simple truth is that it will make things more uncomfortable in the House of Commons."
Ukip candidate Diane James said she had a "very, very, very" realistic chance of winning, predicting that victory would come after three recounts.
"Voting Ukip seems a cost-free way of saying 'we're hurting'," education secretary Michael Gove admitted to the Telegraph.
"People understand there is no alternative to the tough decisions David Cameron has made. But sometimes there are people who are tempted to cast a protest vote.
"My experience is people who are voting Ukip don't come particularly from the Tory stable. There are about four or five Ukip voters I encountered on previous times I've been here. One was ex-Lib Dem, one was ex-Labour."
James has proved a confident and resilient campaigner in the Hampshire constituency, with a bustling office on the high street and a well organised campaign system.
She has also been aided by a series of gaffes from Tory candidate Maria Hutchings, who faced controversy over her comments on refugees, private school, gay marriage, abortion and David Cameron's decision to enter a coalition.
"They've all said I'm a woman who speaks her mind and I'll say it as it is. If people ask me a question on the doorstep, or journalists, I will give an answer," she told the BBC.
"A vote for Ukip here is going to get a Liberal Democrat through the back door, a Liberal Democrat who believes in an amnesty for 600,000 illegal immigrants, who believes in free movement in immigration."
Ukip brought disgraced former Conservative minister Neil Hamilton and his wife Christine to the constituency yesterday, where they urged voters to back the eurosceptic party.
But the party was also hit by the high-profile defection of Marta Andreasen, one of its MEPs, to the Tories, after a series of explosive comments branding leader Nigel Farage a "Stalinist" who is not serious about getting into power.