Nick Clegg has accused the Conservatives of "kidding themselves" on the economy.
The Deputy Prime Minister told the BBC's Andrew Marr Show that he disagreed with his coalition partner's outlook on the economy, saying their plans were "impossible."
"I just think the Conservatives are kidding themselves and seeking to kid British voters if they are claiming that it is possible to balance the books, deliver unfunded tax cuts, shrink the state and support public services," Clegg said.
"It just doesn't add up," he said following George Osborne's scathing attack on the Lib Dems.
George Osborne has launched an scathing attack on his Lib Dem colleagues, warning they would cause "economic chaos" in a future government.Read the full story ›
David Cameron agrees with George Osborne that some of the coverage of the Autumn Statement was over the top and "hyperbolic".
Mr Osborne this morning complained about a BBC report that said spending cuts would return the UK to the days of The Road to Wigan Pier, George Orwell's seminal 1930s account of working class hardship in northern England.
The Prime Minister's spokesman said Mr Cameron agreed that the comparison was not helpful, saying:
I don't think that they help us have what is important here, which is a clear and sensible and measured debate about the decisions that both are being taken and need to be taken in the future. So, the Prime Minister very much shares the Chancellor's view.
Just as it is important to say, as the Chancellor did, that those types of references are hyperbolic descriptions and I'm not sure help the type of debate we need, it's also right to say that what the Prime Minister, Chancellor and others are focused on is their plan and explaining why their approach is the right one.
Shadow Chancellor Ed Balls has insisted Labour will cut spending to help get rid of the budget deficit, but will do so in a fairer way than the Conservatives.
He told ITV News:
The next Labour government will cut spending to get the deficit down, will get the budget balanced and into surplus as soon as possible in the next Parliament and the national debt falling but we'll make different choices from George Osborne to do things in a fairer way. We will reverse the top rate tax cut and we will have to take the Winter [Fuel] Allowance away from the richest pensioners.
The scale of the Conservatives' planned spending cuts after 2015 would mean the role of the state would change "beyond recognition", the head of the Institute for Fiscal Studies has said.
The IFS said £35 billion of the cuts in spending by Whitehall departments have already happened, with £55 billion yet to come.
If reductions in departmental spending were to continue at the same pace after the May 2015 election as they have over the past four years, welfare cuts or tax rises worth about £21 billion a year would be needed by 2019/20 - at a time when Conservatives are committed to income tax cuts worth £7 billion - said IFS director Paul Johnson.
Mr Johnson said voters would be justified in asking whether George Osborne was planning "a fundamental reimagining of the role of the state".
An online calculator to work out how the new Stamp Duty system will affect homebuyers has been used 500,000 times in the last 24 hours, Treasury Minister David Gauke has announced.
The HMRC Stamp Duty Land Tax calculator has had half a million hits in last 24 hours. Find it at http://t.co/TPcQnllxDw
The Business Secretary has said that taxes must rise to help cut the deficit, whoever is in government after 2015.
Vince Cable claimed the Conservatives' plans to reduce the deficit primarily through spending cuts were "implausible".
I think the plans that he's set out are actually implausible, I don't think they can be realised...whatever government comes in, even a Conservative government, is going to have to increase taxes, for example.
There is going to have to be a better balance, but let's discuss the options and let's have set out before the public and Parliament what the different possibilities are.
George Osborne's Autumn Statement will mean "spending cuts on a colossal scale" after next year's general election, the Institute for Fiscal Studies has said.
ITV News Economic Editor Richard Edgar is at the IFS Autumn Statement briefing.
Paul Johnson of the @theifs reiterates that Osborne's plans mean "huge cuts to come" in public services
Nick Clegg has attacked the Conservatives' post-2015 spending plans, saying it is "undeliverable" to expect the working poor to shoulder the burden of deficit reduction.
My view is what George Osborne has said for the Conservative party plan if they were in government on their own after next May are undeliverable. It is simply not deliverable, either econmically, socially, politically, in my view, to say that all the cuts, and all the savings in the future...will come from further sacrifices from the working-age poor only.
I think, quite understandably many, many millions of people who are in working-age poverty in this country will say 'well why do we have to pick up the tab for the mistakes made by the bankers?'.
The Deputy Prime Minister said planned spending cuts were "achievable", but that the wealthy should be made to contribute more to deficit reduction.