His financial superiority has been evident in the primary states of Texas and Ohio, which vote Tuesday and where he has purchased $7.5 million in advertising to her $4.6 million, targeting early voters, young voters and voters in regions with concentrations of delegates.
Clinton's fundraising more than doubled her January fundraising, when she collected $14 million to Obama's $36 million. Clinton has lost 11 straight contests since Super Tuesday on Feb. 5 and her ability to raise money was all the more notable coming in the midst of defeat.
"It was incredibly gratifying to see people come forth with this vote of confidence in me," Clinton told reporters in Hanging Rock, Ohio. "Obviously this is a tremendous benefit to my campaign."
But Obama has been raising money at an even greater rate and spending it, too. Some estimates place his February fundraising at more than $50 million — which would be about half of what he raised in all of 2007. Obama spokesman Bill Burton would not divulge a total but said: "We've raised considerably more than" Clinton.
Obama's campaign had spent $2.4 million on ads in Ohio as of Tuesday, to her $1.3 million, according to TNS Media Intelligence/Campaign Media Analysis Group, which tracks political ads. Clinton spent $3.3 million in Texas; Obama spent $5.1 million, the firm's figures show.
Clinton began running a new ad in Ohio Thursday, with Ohio Gov. Ted Strickland promoting her as a "fighter." "I think she's a person who has devoted her life to caring about other people, making sure that America works for everyone, not just the privileged few," Strickland says in the ad.
Going after younger audience
Obama is targeting younger audiences in his ads, buying expensive prime time spots on programs such as "American Idol" and evening sitcoms. On Tuesday, for instance, Obama bought 38 spots on "American Idol" broadcasts in Ohio and Texas, and in the two other March 4 primary states — Rhode Island and Vermont. Clinton bought only six spots on the show in relatively small markets.
"She's where most of the traditional political buying is," said Evan Tracey, an ad analyst and president of TNS Media. "He is in the choice real estate — it's the luxury end of political buying."
Obama also bought ad time on such Tuesday night programs as "Big Brother," "The Biggest Loser," and "Jericho," a CBS series with a devoted fan base.
Obama also was getting help from labor unions, even though in the past he has criticized rivals who received help from outside groups.
The Service Employees International Union began spending $1.4 million on ads supporting Obama in Ohio and Texas. The United Food and Commercial Workers International Union was spending nearly $200,000 on ads in Ohio. What's more, the SEIU was spending a total of about $1.4 million supporting Obama through phone banks and door-to-door canvassing in Texas and Ohio.
"We are facing a real wall of money from the Barack Obama campaign," senior Clinton adviser Harold Ickes acknowledged during a call with fundraisers Thursday. "But based on everything we know today, we are confident we have very strong operations there."
Former President Clinton, campaigning for his wife at Bryant University in Smithfield, R.I., said: "If she can win a big victory here in Rhode Island, win in Ohio, win in Texas, she'll be on her way to the White House."
He also said: "We've had a great life. She's going to be fine regardless."
Astounding February for Democrats
Clinton entered February with $9 million cash on hand for the primaries and about $7.5 million in debts. Obama had $18 million for the primary and $1.1 million in debts.
If both candidates raise more than $35 million each this time, that would make February an astounding fundraising month for the Democrats. At that rate, both candidates would break records for contestants in a primary fight.
Obama told reporters on his campaign plane, "I have no idea how much money we've raised, but we've been paying our bills. Right now, I believe we're doing very good."
In their call to fundraisers, Clinton's advisers announced that the campaign had raised the money from 300,000 donors, including 200,000 new contributors, most of them donating through the Internet. Aides said almost all the money was for the primary election.
"We have resources to play in big states coming up: Texas, Ohio, Rhode Island, Vermont and states beyond," campaign Chairman Terry McAuliffe said.
'Set of a chain reaction'
Clinton said reports of her relatively weak fundraising in January and her decision to lend the campaign $5 million started a wave.
"People want this campaign to go on," she said. "It just set off a chain reaction around the country. People start paying attention at different points in a campaign. Now people are engaged."
But some Democrats wondered whether the additional money was too late and not enough to match Obama.
"The Clinton campaign clearly has much more money than they had before, but they are still being dramatically outspent by Obama," said Simon Rosenberg, head of the New Democratic Network, a think tank. "And things don't seem to be trending their way and they don't have a lot of tools to deal with it anymore."