Ed Balls has accused George Osborne of "undermining growth" and his own credibility ahead of Tuesday's GDP figures.
The shadow chancellor warned that unless the UK economy grows by 0.8%, Osborne's borrowing forecasts will be incorrect.
"The fact is on Tuesday, simply to be on track for his plans, the economy's got to grow by 0.8%. I don't hear many people in the City who think that's going to work. If it doesn't work, it undermines his credibility."
Balls warned VAT rises and the pace of deficit reduction had damaged confidence in the economy and it was time to take a cautious route. "If the world is building for a hurricane that's not the time to undermine the foundations of your own house. That's what George Osborne did."
He told Sky News: "Our economy has flatlined in the last six months. It's not growing. That's why the Chancellor is having to admit that borrowing's going to be higher than he's expected. In the end unless you've got more people in work, paying taxes, the economy growing, then it's very hard to get these deficits down. Growth is the key. That is what Britain's badly, badly lacking now as a result of George Osborne's plans."
Balls said the current deficit reduction plans were not working and urged the Chancellor to change course, saying he was "out of touch."
"There is a choice. It doesn't have to be this way. George Osborne has made a risky and reckless choice."
Balls' comments came as the Business Secretary Vince Cable admitted that UK growth "isn't great", telling the BBC he supported more quantitative easing.