Political leaders have locked horns over the economy as the main parties intensified efforts to draw clear general election battlelines over spending cuts.
Tory leader David Cameron accused the Government of putting "naked political considerations" before the national interest by opposing early cuts in public spending.
But Gordon Brown hit back, warning that moving too fast would wreck the "fragile" recovery and accusing the Opposition of being internationally isolated.
They traded blows at rival press conferences ahead of the release of official figures on Tuesday which are expected to suggest Britain has returned to growth after a record 18-month recession.
Mr Cameron said that would be "very good news", but it risks being a blip without urgent action to show the UK is intent on slashing its spiralling £178 billion deficit.
He has promised to make reductions in Labour's £707 billion spending plans for 2010/11 in an emergency budget if the Tories win the general election, expected on May 6.
"If we are going to have to wait until May for an election - and if there is going to be a budget in March - they need to show how they are going to start now," he said.
"Now they are about to tell us that the economy is growing, they have no further excuse to delay action except naked political calculation."
But within an hour, the Prime Minister opened his own press conference with a vehement defence of his bid to fund a "wave of social mobility" to secure Britain's recovery.
Immediate spending cuts would be "the biggest mistake", he countered, and insisted his approach was backed across the world by other governments and the International Monetary Fund (IMF).