Lord Mandelson accused the Tories of being in "disarray" over economic policy today as Labour called on David Cameron to make clear his plans for post-election cuts.
The Business Secretary said the Opposition was either trying to hide proposals which would "strangle the recovery at birth" from voters or had performed a major policy u-turn.
As pre-general election skirmishing continued, Labour seized on weekend assurances by Mr Cameron that there would be no "swingeing cuts" during the first year of a Conservative government.
The Tories previously stated they would move further and faster than Labour to tackle Britain's £178 billion budget deficit in a bid to reassure international markets and stabilise the economy.
However, Mr Cameron said while an incoming Tory government would make an immediate "start", there was a limit to what could be done in the first 12 months when the spending plans for the financial year were already in place.
Shadow chancellor George Osborne said some quick savings could be found by cutting government advertising, consultants and child trust funds for the better off.
Opening a press conference, Lord Mandelson said: "The challenge for the Conservative Party is to be clear about its immediate plans: how much is it planning to take out of this year's spending?
"So far all we see is confusion and disarray."
There would be "imminent dire consequences" of cutting spending too fast, he said.
"The Tories would strangle the recovery at birth. That is why the public is entitled to know the truth. Instead of bobbing around like a cork in water David Cameron should level with the British people.
"The impact on people's livelihoods and jobs could be riding on how the Tories make up their minds on their spending plans for this year.
"What we are witnessing from the Tories is either a dishonest rhetorical gloss to hide their true intentions or a remarkable intellectual collapse.
"Either way, it does not inspire confidence in this Laurel and Hardy duo.
"If Mr Cameron refuses to be clear, if he will not be honest, people will conclude that - for electoral reasons - he is hiding the truth and that the Conservatives' proposed cuts will indeed eat into the recovery and throw Britain back into recession and lost jobs."Reuse content