Barack Obama raised a record $55 million (27 million pounds) in February, beating rival Hillary Clinton's total and ensuring a big-spending battle for the Democratic presidential nomination in the months ahead.
Obama's haul, announced by aides on Thursday, was a fund-raising record for a single month. It trumped Clinton's $35 million in February and gave the Illinois senator some much needed good news after two critical losses in Ohio and Texas.
Clinton dodged a possible knockout blow in the presidential race with the wins over Obama on Tuesday, setting up a long and bruising fight for the Democratic nomination to face Republican John McCain in November's election.
The New York senator raised $4 million over the Internet since her big wins and $6 million since the month began, her campaign said.
Clinton spokesman Howard Wolfson criticized Obama's promise to be more aggressive in the aftermath of Tuesday's losses and likened him to independent prosecutor Ken Starr, a lightning rod for Democratic criticism during the 1998 probe that led to President Bill Clinton's impeachment.
"I for one do not believe that imitating Ken Starr is the way to win a Democratic primary election for president, but perhaps that theory will be tested," Wolfson told reporters.
Starr led an investigation of Bill Clinton, Hillary Clinton's husband, which focused on Clinton's denials under oath about his sexual relations with White House intern Monica Lewinsky.
The House of Representatives impeached Bill Clinton on perjury and obstruction of justice charges, but he was acquitted in a Senate trial. Starr's probe was attacked by Democrats as politically motivated.
Obama said on Wednesday he planned to step up criticism of Hillary Clinton and raise more questions about her national security credentials and issues like her refusal so far to release her recent personal tax returns.
Obama's comments were in response to what his campaign called Clinton's "slash-and-burn" tactics in the contests in Ohio and Texas, where she questioned his readiness to be commander in chief and lead on the economy.
"When Senator Obama was confronted with questions over whether he was ready to be commander in chief and steward of the economy, he chose not to address the questions but to attack Senator Clinton, and that's what we're pointing out," Wolfson said in a conference call with reporters.
