The US deficit will balloon to 13 per cent of gross domestic product this year if Barack Obama’s budget is approved, Congress’s budget watchdog warned on Friday, offering a bleaker assessment of the economy than that of the White House.

Prompting cries of outrage from Republicans and worsening the administration’s prospects of winning approval for its ambitious budget, the Congressional Budget Office said the 2009 deficit would expand to $1,845bn (€1,358bn, £1,279bn) if the budget were passed, almost $100bn more than the administration’s forecast.