Barack Obama announced yesterday that he had smashed fundraising records for a Democrat presidential candidate after receiving $32.5 million (£16 million) between April and June.

The total, of which all but $1.5 million is for the primary elections in which Democrats will choose the presidential nominee, eclipses the estimated $27 million raised by Hillary Clinton – the front-runner.

Many observers have suggested that Mr Obama’s campaign is beginning to falter after a series of diffident displays in presidential debates have added to the impression that he lacks substance and experience.

His campaign’s disclosure of his fundraising receipts shows that his candidacy is still generating extraordinary excitement in the party’s grass roots and on the internet. His money came from more than 258,000 donors, many of whom have made multiple contributions of small sums. “We now have hundreds of thousands of Americans who are ready to demand healthcare for all, energy independence and an end to this war in Iraq,” Mr Obama said yesterday. “That’s the kind of movement that can change the special interest-driven politics in Washington and transform our country.”

Mrs Clinton’s total, which in any other year would itself have been a record for a Democrat candidate, is thought to have come mostly from mining the list of established donors who backed her husband, Bill, in previous campaigns. Under American campaign law, individuals can give a maximum of $2,300 to a candidate in the primary race and another $2,300 for the general election.

It was not clear last night how much of Mrs Clinton’s money was reserved for a later contest against the Republican nominee.

Recent polls have shown that she has widened her lead to about 14 percentage points against Mr Obama, as well as other Democrat candidates such as John Edwards and Bill Richardson. Mr Edwards was expected to declare that he had met his fundraising target of $9 million, down from the $14 million he received in the first quarter of this year, while Mr Richardson is thought to have raised at least $7 million.

David Plouffe, Mr Obama’s campaign manager, said: “Some of our opponents have tried to deflect attention from the obvious power and momentum of the movement we’re building by pointing to national polls that are all but meaningless.” He pointed out that previous Democrat front-runners have seen their polling leads evaporate when other candidates became better known to voters.

Charlie Cook, the National Journal’s respected political analyst, said: “Unfavourable polls rarely force presidential candidates out of races, but campaigns do run out of money because the polls are unfavourable. That judgement day might be approaching.”

The quarterly returns of John McCain are likely to be subject to intense scrutiny when they are published in the next fortnight. He reported to the Federal Election Commission that he raised $13.1 million in January, February and March, a figure easily beaten by two of his Republican rivals, Mitt Romney and Rudy Giuliani.

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