Shadow chancellor Ed Balls has challenged George Osborne to produce a Plan B for economic recovery.
Mr Balls said disappointing figures revealed last week showed the Government's strategy to revive Britain's economy was faltering.
He was speaking after several leading UK economists told the Observer newspaper of their fears for the coalition's growth plans.
Mr Balls said today: "Confidence is down and we are now seeing week by week more evidence the economy is stalling."
He said Labour would cut spending and hike taxes, but slower than the Government.
"The deficit has got to come down, there's no argument about that," said Mr Balls.
"There's no argument there have to be tax rises and some spending cuts. The question is the pace at which you go.
"If you go at a balanced and steady way, the economy recovers, more people are working and paying taxes - that helps get the deficit down. If you go too far and too fast, the danger is it makes it harder."
The Government has pledged to eliminate the deficit by 2015, while Labour went into last year's general election to cut it by half.
But, speaking to Sky News' Murnaghan programme, Mr Balls repeatedly refused to say how much Labour would borrow to fund greater short-term spending to spark growth.
Pressed for specific figures on how Labour would boost growth, he said: "What I can't do now I'm no longer in the Treasury, without seeing all the detailed tax numbers from HM Revenue and Customs, is to tell you exactly where we would be now.
"What I can do is say to you a year ago when we were in Government borrowing came in £22 billion lower than expected because the economy had grown and unemployment was falling.
"The economic impact of our plans would be better for the economy because we would be reducing borrowing but at a steadier pace. He (Mr Osborne) is going too fast and it's not working."
Mr Balls went onto admit he "got it wrong" over bank regulation while a Treasury adviser as Labour pursued a "light touch" regulation policy towards banks, which helped caused the 2008 financial crisis.
He confessed: "We didn't regulate banks in a tough enough way and I was part of getting that wrong."
The shadow chancellor also called for a £2 billion tax raid on bankers' bonuses to fund job schemes to cut youth unemployment.
Meanwhile, Foreign Secretary William Hague defended the Government's economic recovery plan and blamed former Prime Minister Gordon Brown for Britain's record budget deficit.
Mr Hague told BBC1's Andrew Marr Show: "The harsh truth is that Gordon Brown did not leave this country with the luxury of a Plan B or a different economic strategy.
"We have to get down the debt he left, control the deficits he left and if we wavered from that for a moment then economic confidence would be reduced, the confidence of the financial markets would be very severely affected.
"It is vital to continue the course we have started."
Mr Hague said Britain had a budget deficit equal to Greece and Portugal, but the coalition's deficit reduction plan meant the UK could avoid similarly high interest rates.
He said a cycle of debt and slump in confidence was "the most dangerous storm of all", adding: "We have to carry on with the course the Chancellor has set out.
"There are many economists in the International Monetary Fund, the Organisation for Economic Co-operation and Development and the G20 who think that what George Osborne is doing is exactly right."Reuse content