The government is putting the British economy and the pound at risk with its £20bn "borrowing binge", Conservative leader David Cameron has said.
He called for an election so voters could stop a "fundamentally bad decision" being made which would leave the UK in a "dreadful" situation.
He also said he would not match Labour spending plans for 2010 and beyond.
The government says there is almost "universal consensus" in favour of a stimulus and dismissed election calls.
The prime minister's official spokesman responded to questions about an election by saying: "What the public expects is for the government to govern and that is what we are doing."
'Whack up taxes'
Mr Cameron's comments came as a raft of data was released showing the economic downturn continuing.
The British Retail Consortium reported UK retail sales down 0.4% in November on a year earlier.
The Office for National Statistics said manufacturing output fell in October by 4.9% on a year earlier and the Royal Institution of Chartered Surveyors said sales per estate agent fell to 10.6 in November - the lowest level since the survey began in 1978.
I think these Labour politicians have been found out and just as before they should be punished for a generation for their economic crimes
The government announced a series of measures to try to boost confidence last month, including a cut in VAT from 17.5% to 15% to try to get people spending.
But the chancellor said VAT would go back up after a year, National Insurance contributions would have to rise by 0.5% from 2011 together with a new higher rate of tax for earnings over £150,000. There would also be big cuts in public sector spending growth.
Mr Cameron told BBC Radio 4's Today programme it was right to let the "automatic stabilisers" operate - as tax receipts drop and benefits rise.
But he said it was a "massive mistake" to borrow an extra £20bn on top of already high levels of borrowing and to then "whack up taxes later".
He added: "I think that puts the public finances at risk, it puts the currency at risk, it puts the whole economy at risk and I think it will actually delay the recovery."
In a speech to the London School of Economics later, he said he agreed with the government that exceptional measures were needed, but they had to be "the right exceptional measures".
He said the VAT cut was "unconvincing" and said people would not spend and businesses would not invest if they know taxes will rise and the future looked "bleak".
David Cameron either does not understand the nature of the economic problems facing us, or he simply doesn't care
Yvette Cooper Chief secretary to the Treasury
Labour's plans to cut the growth of public spending started too late, he said. Announcing that a Tory government would abandon Labour's spending plans from 2010, he said to avoid tax rises borrowing had to be brought under control now.
He said Britain was "on the brink of a fundamentally bad decision" and the only way out was to hold an immediate general election.
"I think these Labour politicians have been found out and just as before they should be punished for a generation for their economic crimes," he said.
The government says there is almost a "universal global consensus" on the need to boost economies during the downturn and said failure to take action now would mean a longer and deeper recession.
But Mr Cameron said finance experts such as the heads of the International Monetary Fund had said a fiscal stimulus "is a good idea if you can afford it" and said the government were set to leave the UK in a "dreadful" situation.
He also referred to the governor of the European Central Bank, Jean-Claude Trichet, who told the BBC on Monday: "If you augment too much your own borrowing, you might be punished by markets.
"If you are at the limits of what you can do, you can lose more with absence of confidence and loss of confidence than you would gain from the simple channelling of additional spending."
However chief secretary to the Treasury Yvette Cooper said Mr Cameron's plans meant cutting public spending during a recession.
"That's the money that helps support jobs, that helps support the economy - right now," she told the BBC.
"I think that's hugely irresponsible and what it shows is David Cameron either does not understand the nature of the economic problems facing us, or he simply doesn't care."
Liberal Democrat Leader Nick Clegg said Mr Cameron was determined "to do nothing" while Gordon Brown "borrows billions of pounds to do the wrong things".
He said rather than fund a "here today gone tomorrow" VAT cut, borrowing should be spent on things like "insulating homes, building social housing and reopening rail lines".
"This would create jobs now and make sure that we build a green economy for the future," he said.
A Populus survey for the Times on Tuesday suggested 40% of people trusted Mr Brown and chancellor Alistair Darling to fight the recession, compared with 31% for Mr Cameron and shadow chancellor George Osborne.
The telephone survey of 1,505 adults, taken between Friday and Sunday, suggests a six point increase on that issue since the pre-Budget report on 24 November.
But it also suggests the Conservatives still have an overall lead among voters with 39% support, compared with Labour on 35% and the Lib Dems on 17%.
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