Alistair Darling has defended putting off difficult decisions about the deficit and denied hiding a tax hike for millions with his Budget speech.
The Tories have accused the Chancellor of concealing a tax rise for 30 million workers from a freezing of tax bands.
Opposition MPs and some economists have also claimed he failed to set out a credible strategy for cutting the nation's record debt.
But Mr Darling hit back, accusing the Tories of being "conspicuously silent" on their own plans for taxes and spending cuts. He said: "If we took public spending away now we'd risk tipping the country back into recession. That is not a risk I'm willing to take."
On tax allowances, he claimed they were frozen because they were set at a time of negative inflation in September. He said increasing them as the Tories have suggested would cost £2 billion. "If that really is their policy they need to say where the money is coming from," he told GMTV.
The Chancellor's budget drew up the battlelines for a general election expected on May 6 by squeezing the better off to fund help to new homebuyers, the elderly and the young unemployed.
In his final parliamentary set-piece before the country goes to the polls, he said he was determined those who did well in the good years "should now pay their fair share of tax".
However the Tories warned that tens of millions of ordinary workers would be hit by an effective tax increase with a freeze on personal allowances, despite a 3.7% retail price inflation rate.
Shadow chancellor George Osborne attacked the freeze, contained in the detailed figures in the Budget "red book". "Thirty million working people will be hit by this new Labour stealth tax. The Chancellor said nothing about the biggest tax rise in the Budget," he said.
"That tells you everything you need to know about Labour's cynical tricks and their priorities: the bill for Gordon Brown's economic mistakes is going to be paid by every working family."
