Mitt Romney and the Republicans raised about $21 million more than President Obama and the Democrats during the first 17 days of October, according to numbers released by the two campaigns on Thursday, a period that saw Mr. Romney rising in the polls and holding his own in debates against Mr. Obama.
Mr. Obama announced on his Twitter account that his campaign and the Democratic National Committee had taken in $90.5 million after surpassing Mr. Romney in August and September. Mr. Romney and the Republicans announced this morning that they had raised $111.8 million during the same period, the final days for which the campaigns are required to report their fundraising before the Nov. 6 election.
The new fundraising puts the candidates on pace to raise as much as a billion dollars each with their respective parties by Election Day, breaking the record Mr. Obama and the Democrats set four years ago and marking 2012 as the most expensive election in history. Through Oct. 17, Mr. Obama and the Democrats had raised about $1.06 billion, according to past filings with the Federal Election Commission and tallies from the campaigns. Mr. Romney and the Republicans had raised about $952.2 million, including some money for the party's Congressional efforts.
While Mr. Obama spent heavily early in the campaign to invest in efforts to identify and turn out voters, those efforts have left Mr. Romney and the Republicans with more cash to play with in the final weeks of the election, money that could finance a late surge of advertising. Mr. Romney and the Republicans ended September with a cash advantage of about $34 million.
Neither candidate has yet filed detailed reports with the F.E.C. for the October period, making it difficult to assess which side had more cash on hand going into the final three weeks of the election. Mr. Romney's campaign said the combined cash on hand for Republican efforts was about $169 million. Mr. Obama did not release a cash on hand total.
