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Democratic presidential candidate John Edwards reversed course Thursday by signing onto the public financing system he once rejected with the belief he could raise more money on his own.

The 2004 vice presidential nominee claimed higher moral ground in the debate over money in politics while announcing the change. But it comes after he brought in far fewer dollars than rivals Barack Obama and . Hillary Rodham Clinton.

"It is worrisome seeing the amount of money that is being raised in this campaign," Edwards said on CNN. "This is about taking a stand, a principled stand, and I believe in public financing."

Money for the public financing fund comes from taxpayers who agree to set aside $3 from their income taxes. Candidates who take from the fund must comply with spending limits.

Edwards' decision could put him at a disadvantage against his rivals and undermine the perception that he can win the nomination. He insisted he has enough money to run a serious campaign.

Edwards pointed out that Clinton recently has been voicing support for the public financing system. But she was the first candidate in history to announce she would opt out of the system for both the Democratic primary and the general election.

"We should find out if she means what she says," Edwards said. He challenged Clinton and Obama to join his pledge — an unlikely prospect.

Obama's campaign told the leaders of the Service Employees International Union in a private meeting this week that a candidate would need $80 million to $100 million to compete in the unprecedented 25 states that hold elections in the first month of voting — and only Obama and Clinton can do that.

After hearing the presentation, SEIU postponed a decision on whether to endorse Edwards — a sentimental favorite — until after the third-quarter campaign finance deadline. That deadline is Sunday and candidates are expected to disclose their overall totals.

In the first six months, Obama raised $58.5 million and Clinton collected $52 million. Edwards raised $23 million.

Edwards could get up to $21 million in public money for the primary, but his overall spending on the primary elections could not exceed about $50 million. Candidates eligible for public financing receive matching payments from the federal government for the first $250 of each individual contribution they raise.

Edwards said he will take public financing "through the campaign, period." But Edwards advisers said later that if he wins the nomination, he wants to get the Republican nominee to agree to take public financing as well.

Edwards also would be limited in what he spends in each state. The current spending limit for Iowa, for instance, is $1.5 million. That figure, however, does not count money spent on staff, fundraising and several other costs that could significantly increase the base limit.

Still, Edwards has spent a great deal of time in Iowa and his campaign team will eventually have to prove to the Federal Election Commission that it did not exceed that threshold.

Earlier Thursday, Edwards appeared in forum sponsored by MTV and MySpace where he took questions from a live audience and via online instant message. One online question noted his connection to subprime mortgage lenders that have foreclosed on homes in New Orleans.

In August, Edwards redirected roughly $16 million invested in Fortress Investment Group after learning that two subprime mortgage companies it owned had foreclosed on 34 New Orleans homeowners. Fortress had paid Edwards nearly half a million dollars last year for consulting advice.

Though Edwards used his own money to start a fund to help those homeowners, he will not do the same in Iowa, where 107 homeowners face similar foreclosures, the Des Moines Register reported Thursday.

"New Orleans I believe, is a unique situation," said Edwards, who argues that voters will judge him based on his longtime efforts to help working families, particularly in rural areas like where he grew up in South Carolina.