Gordon Brown's two-day old Budget forecasts were in jeopardy last night after an unexpected deterioration in the public finances last month, official figures showed yesterday.
The Treasury is just £300m away from missing his target for the current budget deficit, which is used to measure the Chancellor's cherished golden rule of balancing the books over the economic cycle.
A fall in tax receipts and a rise in spending left a surplus on public sector net borrowing of £81m, more than £2bn worse off than a year ago. This pushed the current budget deficit - the measure for the golden rule - to £15.8bn, just £300m below the Chancellor's forecast of £16.1m.
While February is normally a strong month for receipts, March is typically a high-spending month as government departments spend their allocations ahead of the end of the financial year.
Figures from the Office for National Statistics show that the average current budget deficit for March over the previous six years has come in at £1.35bn, which would mean he would miss his Budget forecast by £1bn.
Economists are already sceptical of the Chancellor's claim that he can turn a £16.1bn deficit into a £4bn surplus within just three years.
John Hawksworth, the head of macroeconomics at the accountants PricewaterhouseCoopers, said he expected next year's current budget to come out £6bn worse than the £5bn Mr Brown announced on Wednesday. "This would wipe out the already wafer-thin £6bn margin that the Treasury projected it would meet the rule in the current cycle," he said. "The probability of meeting the golden rule on current spending plans is almost exactly fifty-fifty."