Nigel Farage boasts that UKIP could defy the odds to win three-horse race in Eastleigh by-election Nigel Farage claims: 'We could see a UKIP win' Bookies report UKIP are 'roaring into contention' ahead of polling day By-election is a must-win for both Cameron and Clegg Tory MP David Davis warns: 'I think if we came third it would be a crisis' UKIP could secure its first elected MP in a dramatic by-election upset, leader Nigel Farage claimed today as he boasted his party was "coming up on the rails" to overtake both the Liberal Democrats and the Tories in Eastleigh. With voters going to the polls tomorrow to choose a replacement for disgraced Lib Dem cabinet minister Chris Huhne, Mr Farage said UKIP supporters would vote for his party's candidate Diane James "in blood" to express their anger at the bigger parties. Recent polls have put UKIP comfortably in third place, behind the Tories in second and the Lib Dems ahead with a five point lead. UKIP leader Nigel Farage, pictured campaigning in Eastleigh today, raised the prospect of a shock win for his party in tomorrow's by-election But activists on the ground report a groundswell of support for UKIP in recent days, taking support from both coalition parties. Mr Farage told LBC 97.3: "It started off as a two-horse race with the Liberal Democrats and Conservatives ahead. Over the course of the last week we have been coming up on the rails. We have almost drawn level with one full day's campaign to go. What we have got here is a very exciting three-way marginal. I think this is the toughest by-election to call we have ever seen. Comedian John O'Farrell, Labour's candidate in Eastleigh, was slammed by David Cameron today over were "extraordinary" comments about IRA terrorism and the Falklands War. The Prime Minister urged Labour leader Ed Miliband to disown the satirist's admission - in a 1998 book - that he felt "disappointment" Margaret Thatcher was not killed in the 1984 Brighton bomb. Mr Cameron added that Mr O'Farrell (pictured, right, with Mr Miliband) had shown "a shocking lack of national patriotism and pride" by writing that he had wished Argentina would be victorious in the 1981 Falkland conflict. It was "absolutely staggering" that someone standing for public office had written of feeling a "surge of excitement at the nearness of Margaret Thatcher's demise and yet a disappointment that such a chance had been missed," Mr Cameron said during Prime Minister's Questions Mr Miliband failed to respond. Mr O'Farrell, who was campaigning with Cherie Blair in Southampton today, took to Twitter to defend himself, posting: "I wrote an honest memoir and volunteered this fleeting bad thought from 1984 to illustrate how hatred can poison politics." Turnout makes a hell of a difference. People who have said they will vote UKIP will go out and vote for UKIP in blood. We could see a UKIP win," he added, although he accepted "the odds are against." Bookies reported a surge in bets on a UKIP win. Alex Donohue of Ladbrokes said: "UKIP are roaring into contention at the eleventh hour. Given the added safety net political punters have never been keener to back Farage's party. We've never seen stakes this high in a by-election. Betting records have been smashed many times over. UKIP MEP Roger Helmer said he thought the party would secure a record share of the vote for a by-election, adding: 'If we do I shall drink a great deal of champagne.' In the Commons today David Cameron urged Tory MP 'who are not there already to make their way to Eastleigh this afternoon and support Maria Hutchings in the by-election campaign'. Former Tory leadership challenger David Davis told BBC TV's Daily Politics: '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. 'Lets be clear, it's not gonna 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.' The Eastleigh contest has been billed as a must-win for both David Cameron and Nick Clegg, to reassure their party grassroots that they can defeat their coalition partners in a straight fight. An opinion poll by former Tory deputy chairman Lord Ashcroft suggested that in the Hampshire seat of Eastleigh, where voters go the polls on Thursday, the Lib Dems are clinging on to a five-point lead over their coalition partners. All the main parties stepped up their campainging efforts today in a last ditch bid to win support. Justice Secretary Chris Grayling was leading the Tory drive, while Deputy PM Nick Clegg was in the constituency to shore up votes for Lib Dem candidate Mike Thornton. Labour's candidate, comedian John O'Farrell, has trailled in the polls and been dogged by comments about the IRA bomb attack which nearly killed Margaret Thatcher and wishing Britain had lost the Falklands war. Today he was joined by Cherie Blair on the campaign trail, although Labour insiders have given up hope of making any in roads in the crucial southern seat. Labour's candidate John O'Farrell was joined on the campaign trail by Cherie Blair, meeting Angela and Millie Lancaster 3, at Southampton's Children's Hospital Tory candidate Maria Hutchings was joined by Justice Secretary Chris Grayling on the last day of campaigning The Lib Dems had been confident that Huhne's resignation after pleading guilty to perverting the course of justice would not damage their support. But the party has since become embroiled in the Lord Rennard "groping" scandal, with up to 10 women claiming he behaved inappropriately towards them when he was the party's chief executive until 2009. During his weekly radio phone, Mr Clegg said it was a 'fair question' to ask why voters would trust his party given its record of scandal. 'He told LBC 97.3: 'My sense is that actually when people vote they ask themselves who's going to create jobs, who's going to deliver fair taxes and who's going to protect green spaces in the Eastleigh area and who is going to be an outstanding local MP for my area. The Lib Dems are defending a 3,684 majority in the Eastleigh seat, with UKIP expected to make the biggest gains A poll by Lord Ashcroft this week put the Lib Dems five points ahead of the Tories 'And on all of those counts, delivering jobs, increasing the number of apprenticeships, delivering fairer taxes, lower council tax, fairer income tax and protecting green spaces I think everybody accepts in Eastleigh that it's the Liberal Democrats who've got the record of action.' Losing Eastleigh would be a major blow to Mr Clegg, and pose a serious threat to his leadership ahead of the party's spring conference next week. It would mark the first time a prime minister has taken a seat in a by-election since Margaret Thatcher in her Falklands pomp in 1982. The Tories must also secure victory to prove Mr Cameron can make electoral gains from his coalition partner, in the hope of landing an overall majority in the 2015 election. UKIP leader Nigel Farage claims there has been a surge in support for Diane James, his party's candidate in Eastleigh Must win: David Cameron and Nick Clegg, both pictured today, each need to secure victory in Eastleigh to prove to their party activists that they can defeat their coalition partners in a key seat Education Secretary Michael Gove admitted the Tories risk losing votes to UKIP. Campaigning in Eastleigh he said: "Voting UKIP seems a cost-free way of saying we're hurting. 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," he told the Daily Telegraph. The Tories have warned voting for UKIP risks handing Mr Clegg a crucial win. Former UKIP MEP Marta Andreasen, who has defected to the Tories, appeared in Eastleigh alongside Cabinet ministers including Michael Gove and Patrick McLoughlin to warn the "cold reality" was a "vote for UKIP in Eastleigh is simply a vote to give Nick Clegg another pro-Euro MP."