The campaign released the figure on Sunday, one day before it must file a detailed report of its monthly finances with the Federal Election Commission.
Obama's money is fueling a vast campaign operation in an expanding field of competitive states. It also has underwritten a wave of both national and targeted video advertising unseen before in a presidential contest.
Campaign manager David Plouffe, in an e-mail to supporters Sunday morning, said the campaign had added 632,000 new donors in September, for a total of 3.1 million contributors to the campaign. He said the average donation was $86.
The Democratic National Committee, moments later, announced that it raised $49.9 million and had $27.5 million in the bank at the start of October. The party has been raising money through joint fundraising events with Obama and can use the money to assist his candidacy.
Obama's numbers are possible because he opted out of the public financing system for the fall campaign. McCain, the Republican nominee, chose to participate in the system, which limits him to $84 million for the September-October stretch before the election.
Obama's monthly figure pushed his total fundraising to $605 million. No presidential candidate has ever run such an expensive campaign. His campaign raised $65 million in August, his previous best.
"The overall numbers obviously are impressive," Plouffe said in a campaign video. "But it's what's beneath the numbers in terms of average Americans who have had enough, who want a change and who are really fueling this campaign."
Obama had initially promised to accept public financing if McCain did, but changed his mind after setting primary fundraising records. His extraordinary fundraising is bound to set a new standard in politics that could doom the taxpayer-paid system. Many Republicans have begun to second-guess McCain's decision to participate in the program.
With his money, and a favorable political wind at his back, Obama has secured his foothold in states that have voted for Democratic presidential candidates in the past. But he has also been able to expand the contest to reliably Republican states, forcing McCain and the Republican Party to spend their money defensively.
Plouffe pointed out that the campaign is now spending resources in West Virginia. Obama running mate was scheduled to campaign in Charleston, W.Va., on Friday and the campaign has secured television advertising in the state for the next two weeks, according to ad data obtained by The Associated Press. Plouffe hinted at further expansion, noting that public opinion polls show the race tightening in Georgia and North Dakota.
As much as Obama raised, he needed a big fundraising month to justify his decision to bypass the public finance system. Financially, he has been competing not only against McCain, but against the GOP, which raised $66 million in September.
The combined Obama and DNC totals for September now give the Democrats a distinct financial advantage going into Election Day, just 16 days away.