Respected finance experts have questioned whether the chancellor has unveiled a vote winning Budget.

Offering its critique of the Budget, the Institute of Fiscal Studies rejected suggestions that the chancellor's announcement will woo floating voters.

"If Labour backbenchers were hoping for a big giveaway Budget to kick off the government’s re-election campaign, they should have been sorely disappointed," the IFS said.

"Gordon Brown offered some modest sweeteners to pensioners, motorists and homeowners, but what he gave with one hand he took away with the other."

The think tank says the chancellor's few giveaways - such as the £200 council tax refund - were paid for largely by "a predominantly one-off hit on North Sea oil companies".

But the IFS goes on to warn that the chancellor's prudence may lessen over future years.

"The net impact of the Budget measures on the public finances is a tightening of £265m next year, but this becomes a net giveaway as the tax hit on oil companies diminishes," it notes.

"The giveaway in future years could end up being larger still if the chancellor feels it necessary to repeat this year’s one-off handout to pensioners, as past experience suggests he might."

It also has a warning to the Treasury over Brown's much vaunted fiscal rules.

"We estimate that on the Treasury’s own forecasts and historic forecasting errors that the chancellor now has a 65 per cent chance of meeting the golden rule over the current cycle," he said.

"So it is clearly touch-and-go whether or not the rule will be met."

And it also warns that both opposition parties have been given room for manoeuvre by the chancellor's Budget blueprint.

"The Liberal Democrats and Conservatives can credibly promise either to implement the Budget giveaways, or spend the money on their own priorities," says the IFS.

"The £4 billion of tax cuts offered by the Conservatives can be offered in addition to, not instead of, those announced in the Budget.

"If the Conservatives win an election later this year, pensioners would see their council tax bills fall this year by £200 thanks to Gordon Brown, and would then see them halved in 2006 thanks to Oliver Letwin’s first Budget."