John McCain's campaign said he would accept public financing in the general election were his Democratic opponent to do so, raising the prospect that the most expensive election in US history may conclude in a taxpayer-funded finale.
Rick Davis, Mr McCain's campaign manger, yesterday pointed out that Barack Obama, who many now see as the likely Democratic nominee, had already pledged at the beginning of his presidential campaign to accept public financing were his Republican opponent to do so.
Mr Obama, who has since broken all fund-raising records, obtained a ruling from the Federal Election Commission last year that allowed him to raise money privately for the general election but to return it to donors at the start of the poll were he to face a like-minded Republican nominee.
In contrast, Hillary Clinton, his Democratic rival, made no such pledge at the start of her campaign a year ago and has said she would rely on private donations for the primary race and the general election. Mr McCain is notoriously bad at fundraising and provoked anger among Republican conservatives when he co-sponsored a campaign finance reform bill three years ago.
"Mr Obama has said he will abide [by his pledge]," said Mr Davis. "The only reason Senator McCain would ever not participate in public financing is if his Democratic opponent didn't." But Mr Davis added that he would be tempted were Mr Obama to discard his earlier commitment.
Under US public financing rules, taxpayers voluntarily check a box on their tax return giving $3 to the system. But a dwindling number do so which means candidates would only get about $85m (£43m) a piece in the 2008 election - compared with the $230m to $280m that John Kerry and George W. Bush each spent in 2004.
"I have to say that if I was raising $32m a month [the record Mr Obama raised in January] then I would have to think it through," said Mr Davis. "Obama would certainly be more likely to break that pledge than John."
A spokesman for the Obama campaign said: "We are focused on one race at a time. We will address that question in the general election."
