Liberal Democrat business secretary Vince Cable has delivered a withering attack on the Conservative party over its "obsessive" economic policies.
He accused chancellor George Osborne of lying by suggesting he can cut the deficit without raising taxes.
And he claimed the Conservatives were ideologically obsessed by public spending cuts as a way of destroying the welfare state.
He said he would want to see increases in both taxation and borrowing to pay for policies to protect the worst off and maintain public services.
In a fiery conference speech which specifically targeted the Tories over the economy, Cable attempted to distance the Lib Dems from their coalition partners ahead of the general election.
But it also indicated Cable's personal leanings towards Labour, seen as further evidence he would rather do any post-election deals with Ed Miliband than David Cameron.
Referring to the Tory pledge to cut taxes while also reducing the deficit, Cable said: "More taxes will be needed to contribute to deficit reduction and also to address unacceptable inequalities.
"Any politician who tells you that the next Government can balance the budget and avoid tax increases is lying to you."
He also accused the Conservatives of being wedded to cuts, saying: "The Tories are ideologically obsessed by cuts. They see it as a way of destroying public services and the welfare state, which they detest.
"Their proposal to take another £25bn or more out of welfare and unprotected Government departments will do great harm to valuable services.
"To imagine otherwise is fantasy. We will categorically not go along with this," he said.
He also stressed his own dislike of the Conservatives, saying: "We worked with the Tories because voters chose them as the largest party, not because we liked them, or because we are like them."
His speech was just the latest in a series of assaults on the Conservatives and, in particular, the pledge at their conference last week to cut the deficit while also cutting taxes.