UK Parties Leaders In Campaign Final Stages Before May 7 General Election

David Cameron meets supporters on the election campaign trail in West Yorkshire

With just three days left before Thursday's knife-edge General Election, party leaders were throwing themselves into a frenetic final round of campaigning.

But David Cameron was accused of snubbing the last major set-piece event of the campaign, as it emerged he would not attend a Westminster hustings staged by community organizing charity Citizens UK, where around 2,000 voters will be addressed by Ed Miliband and Nick Clegg.

Instead, Mr Cameron was travelling to the South West to speak to supporters at a Conservative rally, where he will tell voters that they face an "inescapable choice" between him and Mr Miliband as Prime Minister.

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The Times reported that senior Labour figures were warning the party should not attempt to form a government backed by smaller parties if it ends up with significantly fewer seats than the Tories.

Analysis for the Sunday Times by YouGov pollster Peter Kellner forecasted Mr Cameron will have 283 MPs and Mr Miliband 261, with 60 nationalists and Greens presenting the possibility of an "anti-Tory" alliance of the kind favoured by the SNP's Nicola Sturgeon.

Mr Miliband has ruled out a formal coalition or deal with the Scottish National Party, but there is speculation he may try to lead a minority administration reliant on nationalist votes to get its agenda through.

Yesterday, Ms Sturgeon told a televised BBC1 Scottish leaders' debate the SNP would be ready to vote down a Labour budget it disliked and use its House of Commons "clout" to get a better deal.

One unnamed Labour frontbencher was quoted in The Times as saying a minority Miliband administration would have "questionable legitimacy" if the party had 12 fewer MPs than Conservatives.

Another reportedly said the party should accept opposition and seek a new leader if the arithmetic required it to rely on the SNP for a mandate to govern, as the country would not "forgive" them if they "come second and try and cling on".

But asked whether Mr Miliband could remain in the post even if he failed to become prime minister, shadow health secretary Andy Burnham - a likely contender in any leadership contest - told the Financial Times: "Of course he can."

The Telegraph UK published a list of the 23 constituencies which it said the Conservatives have identified as targets they must win to secure an overall majority.

The list included several seats held by Liberal Democrats in the 2010 Parliament, including Business Secretary Vince Cable's Twickenham, Energy Secretary Ed Davey's Kingston & Surbiton, Bath, Eastbourne, Chippenham and Cheadle, but only one Labour-held seat - Halifax.

Around 2,200 voters are expected to attend the Citizens UK elections assembly, where they will fire questions at Mr Miliband, Mr Clegg and Conservative Culture Secretary Sajid Javid.

The group's trustee Kaneez Shaid said: "We are disappointed that David Cameron has chosen not to attend our event, despite the fact he promised in 2010 to attend two of these assemblies, which he has not done."

Mr Clegg said the decision was typical of the "bloodless and uninspiring" campaign run by the Conservatives, while Labour's campaign vice-chairwoman Lucy Powell accused him of "ducking" the encounter with voters because "he can't defend his record".

But Tory sources said it had been made clear some time ago that Mr Cameron would be unable to attend due to campaigning commitments elsewhere in the country, and that Mr Javid would take part.

A spokesman said: "Sajid Javid is delighted to represent the PM and the Conservatives at this Citizens UK event. We seek to continue the strong relationship built with Citizens UK over the course of the last Parliament."

Following his pleas for Ukip and Liberal Democrat supporters to vote tactically for Tories to help keep him in Downing Street, Mr Cameron will frame the election as a straight choice between him and Mr Miliband.

"It's the start of a week when Britain will decide its future. By Friday you'll either have Ed Miliband or me as your prime minister," he will say.

"It's that simple - an inescapable choice: me leading a strong and stable Government, or with him: the chaos of being held to ransom by the SNP.

"Your vote can and will make a difference. It’s that close."

Meanwhile, Mr Clegg will promise to use the proceeds from a £227 million fine imposed for financial misconduct on Deutsche Bank to fund air ambulance trusts and buy equipment for hospitals.

The Lib Dem leader said the move would "drastically improve patient outcomes and save thousands of lives a year".

Responding to the claims in The Independent, a spokesman for Mr Crosby's lobbying firm CTF Partners said: "This is another politically motivated, gratuitous attempt to republish baseless and false allegations made two years ago. It has been a matter of public record since 2013 that CTF provided polling and analysis to (healthcare providers group) H5 in 2010, which ended in June 2011.

"The contents of this document were presented to scores of Labour, Liberal Democrat and Conservative MPs at an event at the House of Commons in 2010 organized by a former Labour councillor. Briefings of information in this document were also widely circulated at that time.

"Any claim that this widely known information somehow represents a conflict of interest with work being undertaken four years later is completely unfounded and categorically wrong."