The Conservatives are under growing pressure to spell out clearly whether they could strike a deal with Ukip in a hung parliament.

Nigel Farage described David Cameron as “somebody we can sit down with and talk to” in those circumstances, but insisted his party could never work with Labour because of its opposition to a referendum on EU membership.

Both Mr Cameron and Chancellor George Osborne refused to rule out co-operating with Ukip, prompting Labour to challenge the Prime Minister to reject the “poisonous proposition” of a deal with Mr Farage’s party.

The Tory chief whip Michael Gove slipped into German when he was asked about a possible arrangement with Ukip, saying: “Nein danke.”

However, the Defence Secretary, Michael Fallon, later took a more unequivocal line.

Asked if the Tories would be prepared to work if necessary with Ukip if necessary, he replied: “No. We have already said we are going for a majority government. We are not in the business of doing deals.”

Experts' predictions for the general election Show all 10 1 /10 Experts' predictions for the general election Experts' predictions for the general election Andrew Hawkins (ComRes) Just as the polls in 2010 pointed to no overall majority for any party, the overwhelming evidence points to Labour either being the largest party or getting a small majority, probably below 20. The Lib Dems and SNP should each win between 25 and 35 seats, with single-figure wins for both Ukip and the Greens. Experts' predictions for the general election Joe Twyman (YouGov) I predict it will be close. I predict a few tremors, though earthquakes are unlikely. I predict the eventual winner may not be the direct result of public opinion, but instead the outcome of political negotiations. It’s too early to predict numbers given all the uncertainties surrounding (among other things) Ukip, the SNP and the Lib Dems. It is possible that it will be close between Conservative and Labour in terms of both votes and seats. The Lib Dems might retain 20-30 seats and the balance of power, despite small gains for the SNP, and at most half a dozen Ukip seats. Gun to my head? Labour minority government. Rex Experts' predictions for the general election Ben Page (Ipsos MORI) A mug’s game for this election months away, but my predictions in order of likelihood: most likely a hung parliament or coalition of some kind, closely followed by either a small Labour majority or an equally small Conservative majority. Given how close the parties are, the unknown performance of Ukip in key marginals, the effect of incumbency on Lib Dem losses, the final size of SNP surge and so on, to be more precise is simply foolish! Professor Tetlock, who found that forecasts by experts were only slightly better than throwing dice, weighs heavily upon me! Rex Experts' predictions for the general election Rick Nye (Populus) I can see a hung parliament, where Labour is the largest party in terms of seats – though not necessarily in terms of votes, with the Lib Dems having 30 seats or fewer, the SNP having up to 20 seats and Ukip having no more than five seats. In short, it’s going to get messy and stay messy for some time to come. Experts' predictions for the general election Nick Moon (GfK) I can’t recall there ever being an election more difficult to predict than this one. I’m confident no party will have an overall majority, with the Tories probably the largest party but no single partner for a viable coalition, with the Lib Dems on 25 seats, the SNP 20, Ukip three, and the Greens one. Experts' predictions for the general election Damian Lyons Lowe (Survation) We might have expected a workable Labour majority, were it not for the wild-card rise of the SNP in Scotland. Survation’s December Scottish polls suggest an almost complete wipeout by the SNP in Scotland and result in 40+ seat gains – mostly at Labour’s expense. My current predictions are: Labour the largest party by 40-50 seats over the Tories, no overall majority; Tories 235-255 seats; Lib Dems 20-30 seats; SNP 30-40 seats – maybe held back from potential support level by opposition incumbency and tactical voting by pro-unionist voters. Finally, Ukip, 5-10 wins from Conservatives, including Rochester and Clacton, and potentially a single Labour-seat surprise. Experts' predictions for the general election Michelle Harrison (TNS) The battleground over the next three months is at the kitchen table – the difference between what the statistics tell us about the economy, the experience that Britons are having of managing their household budgets, and where – and if – they believe politics can make a difference. In this regard, the disconnect with the major political parties is more interesting than the horse race. Experts' predictions for the general election James Endersby (Opinium Research) Our first poll for 2015 shows Labour one point ahead [see above], but polls four months out from an election are snapshots, not predictions. It would be extremely unwise for a pollster to make a firm prediction now. At the moment, Opinium’s estimate on polling day would be the Tories slightly ahead on vote share, but Labour slightly ahead on seats. These numbers are based on a uniform swing, with tweaks to Green and Ukip numbers based on local information: Labour 320 seats, Conservatives 271, Lib Dems 20, SNP 16, Plaid Cymru three, Greens two, Ukip four. A hung parliament with Labour potentially closer to a majority coalition than the Conservatives. Experts' predictions for the general election Martin Boon (ICM) I’ve not recovered from the Scottish referendum campaign yet, and here we go with another wildcard strewn nail-biter. For me, Labour on 30 per cent will only fractionally nudge past their woeful 2010 showing – behind the Tories on 33 per cent – but enough to secure more seats (290 for Labour, 280 for the Tories) on boundary wackiness. The Lib Dems will secure 14 per cent of the vote and 35 seats; Ukip will also get 14 per cent, but that only gets them a couple of seats. As for Scotland, I’m bewildered, but as you asked I’ll say 30 seats for the SNP, which wipes out a breathing-space victory in seats for Labour. Experts' predictions for the general election Lord Ashcroft (Lord Ashcroft Polls) Declined to take part. His spokeswoman said: “As he has said many times, his polls are snapshots not predictions.” Health warning: when The Independent on Sunday carried out a similar exercise in April 2010, at the start of that year’s election campaign, eight out of eight pollsters predicted a Conservative overall majority. Rex

Before the election Tory chiefs brushed off demands from some of their MPs and activists for informal local pacts with Ukip, which has eaten into Conservative support in many constituencies in the south and east of England.

Ukip’s two MPs are former Tory backbenchers and most of its top target seats, including Thanet South where Mr Farage is standing, are currently held by the Conservatives.

In a letter to Mr Cameron, the shadow Health Secretary, Andy Burnham, claimed it was clear the Tory leader was preparing to do a deal with Ukip and urged him to “come clean” on the subject.

“The real terms of a deal would see the end of the NHS as we know it,” Mr Burnham claimed.

“Your deal with Ukip is a poisonous proposition that would deny working people the care they rely on from a service they cherish.”

Mr Farage, who was considered to have performed strongly in Thursday night’s debate, ruled out a post-election deal with Mr Miliband, explaining: “He has said he will not give the British people a referendum on the great European question."

But the Ukip leader said the Prime Minister “at least has been forced into promising that, and so after the election he is somebody we can sit down and talk to”.

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