Senator Barack Obama collected more than $13.7 million in the last four days of August during a record-shattering fund-raising month, with donations spiking the day after he accepted the Democratic nomination when Gov. Sarah Palin of Alaska was named to the Republican ticket, new filings with the Federal Election Commission showed.

The closing surge of donations, with Mr. Obama topping $4.7 million on Aug. 29, when Ms. Palin's selection was announced, and $3.8 million the following day, helped him raise $65 million in August.

The Obama campaign had already announced its August fund-raising haul, which is more than any other presidential candidate in history, but its official F.E.C. filing offered the first detailed glimpse at how he did it.

The filing, however, only furnishes a partial picture because the campaign does not have to itemize contributions below $200 for the election cycle.

Mr. Obama received more than $22 million in un-itemized contributions, so it is likely that his totals at the end of the month were considerably more than what was revealed in his filing.

The McCain campaign got a surge in donations as well around the Palin announcement, bringing in more than $6.8 million on Aug. 30 the day after she made her debut with Mr. McCain at a rally in Ohio. The spike helped Mr. McCain to his best fund-raising month as well, bringing in more than $47 million.

Mr. Obama significantly outspent Mr. McCain in August, $53 million to $40.6 million. Mr. Obama spent more than $32 million on advertising, almost exactly what he spent the previous month, compared to about $23 million for Mr. McCain in August; Mr. Obama's payroll was $2.7 million, up slightly from the previous month, compared to just $1.1 million for Mr. McCain.

Although the Obama campaign has consistently outraised the McCain campaign, Mr. McCain and the Republican National Committee, which can spend money on his behalf under certain restrictions, actually started September with slightly more cash on hand than Mr. Obama and the Democratic National Committee. That is because of the strength of the R.N.C.'s fund-raising over the last several months and its ability to nurse its resources.

Mr. McCain also received an $84 million infusion from the U.S. Treasury in September after his party's convention under public financing, putting the pressure on Obama fund-raisers to match or exceed their August performance.