With More Than $20 Million, Obama Reports Strong Quarter

Others have turned to the presidential public financing system, which can provide an infusion of cash in advance of the first primaries but also subjects candidates to limits on how they spend those funds. The limits severely restrict spending in crucial early contests, and they cap overall spending prior to the party conventions at the end of the summer to about $50 million.

Republican Rep. Tom Tancredo (Colo.) joined the ranks of those contemplating public financing, saying yesterday that he has reported $1.6 million in contributions to the Federal Election Commission in a request to qualify for federal matching funds. Edwards was the first to formally seek matching funds, and his senior adviser, Joe Trippi, said yesterday that he expects the campaign to receive $10 million in public financing. Sen. John McCain (R-Ariz.) has qualified for matching funds, but he has not yet decided whether he will take the money.

Critics have skewered Edwards's decision as one made out of desperation. But during a conference call yesterday, Trippi framed the decision to take matching money as one grounded in principle and political strategy, not financial need. "People are sick and tired of the corroded, busted, rigged system in Washington," he said.

Clinton spokesman Phil Singer declined to take a direct shot at Edwards but said: "The Edwards campaign says it opted into the public financing system out of principle. Others might come to a different conclusion."

Michael J. Malbin, executive director of the Campaign Finance Institute, said there is still plenty of money to be had.

A study of donations made during the first six months of 2007 found that more than 80 percent of people who donated to candidates in the 2008 race did not give money in 2004.

"More than 8 out of 10 donors who gave in the last presidential election have not weighed in yet," Malbin said. "There's a lot of untapped capacity out there."