The overall totals do not include hundreds of millions of dollars

The overall totals do not include hundreds of millions of dollars being raised and spent by "super PACs" and other outside groups, mostly to benefit Mr. Romney and other Republicans. Groups aligned with Mr.  Romneyhave spent $302 million on campaign advertising that they are required to disclose to the F.E.C., compared with about $120 million for groups aligned with Mr. Obama. Tens of millions of dollars more has been spent on issue advertisements whose precise costs are difficult to measure.

"As the Romney campaign and their 'super PAC' allies continue to outspend us on the air, we're making every effort to expand our donor base heading into the final stretch," said Adam Fetcher, an Obama spokesman.

Mr. Romney and the Republicans raised about $21.3 million more than Mr. Obama and the Democrats during the first 17 days of October, according to the disclosures filed on Thursday, as Mr. Romney rose in the polls and performed well in debates, emboldening his supporters.