NIck Clegg: George Osborne is not a decent human being

The attack came amid a furious row over claims David Cameron told senior Liberal Democrats the Conservatives would not win an outright majority.

Tory aides reacted angrily to the suggestion that the Prime Minister had admitted he would be able to govern only as a minority administration or with the help of another party.

They denounced the claim as "100 per cent untrue" and "complete nonsense" and said that it showed that the Lib Dem general election campaign was in a state of panic.

The accusation came from Lib Dem peer Lord Scriven, who also claimed the Tory leader was "lying" over public claims his party would have a majority in the House of Commons.

Mr Clegg refused to confirm the main accusation saying that he would not "reveal private conversations".

But he went on to repeatedly accuse the Tories of a "big fat fib", for claiming that they needed only 23 more seats for a majority.

The claim is based on the number of extra seats the Conservatives would have needed to achieve a majority in 2010.

But the Lib Dems said it was wrong to suggest the Tories were going to keep every seats they won five years ago.

The Labour leader Ed Miliband also waded into the row saying: "Cameron appears to have now said he's not going to win the election.

"It says it all about him and about his campaign. We are fighting every step of the way."

Later the Lib Dem leader turned on Mr Osborne saying that if he was "decent he would look the families, the mothers and fathers of disabled children in the eye" and explain the extent of his planned cuts.

Mr Osborne has announced plans to cut £12 billion from the welfare bill after May's election.

But the Conservatives have consistently refused to say where the axe might fall.

The Tories insist that they should be judged instead on their record, and how they have cut the benefits bill over the last five years.

Last week the Lib Dem Treasury Chief Secretary Danny Alexander released details of what he said were Conservative proposals to cut child benefit.

On the campaign trail in Surbiton, south west London, last month Mr Clegg also referenced the planned cuts saying: "George Osborne is a very dangerous man with a very dangerous plan and I will do everything in my power to stop it."

Earlier, Lord Scriven had said: "If David Cameron is going to lie when he knows in his heart of hearts his private polls are showing that the British people are likely to give no party an overall majority, then so be it," Lord Scriven said.

"I don't take back anything I said in the tweet. People are not stupid. The opinion polls show what's happening, the private opinion polls show what is happening.

"When I read ...that David Cameron is not telling the truth to try to scare people to vote then I think that his private feelings do need to be made clear."

In good news for Mr Clegg a new opinion poll appeared to show that he is on course to hold on to his seat, thanks in part to Conservatives voting tactically to try to keep out the Labour party.

The ICM poll showed Mr Clegg seven points ahead of his Labour rival Oliver Coppard, on 42 per cent to 35 per cent.

The poll has asked about Mr Clegg by name, fuelling Lib Dem hopes that personal recognition could help the party to hold on to some of its seats.

Without the names being given, Labour was ahead by 34 per cent to 32 per cent.

The results, however, also suggested that Mr Clegg was reliant on tactical voting by Tories on what one ICM pollster described as "a breathtaking scale".

The Lib Dems have struggled in the polls since entering into coalition government with the Tories in the wake of the 2010 election.

Meanwhile, Mr Clegg will embark on a Land's End to John O'Groats campaign marathon in a last ditch effort to save as many Liberal Democrat seats as possible.

In a final push aimed at defying national opinion polls which suggest his party could suffer a mauling at the hands of the electorate on Thursday, Mr Clegg will take his battle bus on a 1,000 mile journey across Britain.