Democrats Hillary Rodham Clinton and Barack Obama clashed bitterly Monday over Bill Clinton's role in his wife's campaign and Obama's recent comments for Republicans in a presidential debate five days before the pivotal South Carolina primary.

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After a brief discussion of the nation's economic woes, the debate devolved into an angry exchange between the two senators, with Clinton noting Obama had taken campaign contributions from a political patron facing fraud charges and Obama calling Clinton a "corporate lawyer sitting on the board of Wal-Mart."

Clinton and Obama's testy exchange came after Obama defended his comments about Republican ideas and Ronald Reagan:

"You talked about admiring Ronald Reagan," Clinton said.

After back-and-forth jousting between the two and the moderator, Obama said, "You just said that I complimented the Republican ideas. That is not true."

"What I said was that Ronald Reagan was a transformative political figure because he was able to get Democrats to vote against their economic interests to form a majority to push through their agenda, an agenda that I objected to. Because while I was working on those streets watching those folks see their jobs shift overseas, you were a corporate lawyer sitting on the board at Wal-Mart," Obama said.

"So I want to be clear. What I said had nothing to do with their policies. I spent a lifetime fighting -- a lifetime -- against Ronald Reagan's policies. But what I did say is that we have to be thinking in the same transformative way about our Democratic agenda. We've got to appeal to independents and Republicans in order to build a working majority to move an agenda forward. That is what I said," he added. "The irony of this is that you provided much more fulsome praise of Ronald Reagan in a book by Tom Brokaw that's being published right now, as did -- as did Bill Clinton in the past."

John Edwards, who badly trails his two rivals, tried to stay above the fray while pleading for equal time. "Are there three people in this debate, not two?" he asked.

"We have got to understand, this is not about us personally. It's about what we are trying to do for this country," Edwards said to applause from the audience.

Often speaking over each other, Obama and Clinton clashed over their legislative records. Obama questioned why the New York senator had voted for a bankruptcy bill that she later said she was glad hadn't passed, and Clinton criticized Obama for voting "present" on dozens of occasions while a member of the Illinois Legislature.

"Senator Obama, it's hard to have a straight-up debate with you because you never take responsibility for any vote," Clinton said to loud boos. "On issue after issue, you voted present ... Whenever someone raises that, there's always some sort of explanation."

Obama accused Clinton of playing dirty and saying anything to get elected, while Edwards joined Clinton in criticizing Obama for the "present" votes.

Clinton and Obama called for tax rebates for individuals to help with home heating and other short-term needs. But Obama claimed he was first with the idea, saying Clinton had "caught up" with him.

Edwards tried to make a distinction by pointing out that Clinton and Obama supported a trade deal with Peru. "South Carolina has been devastated by NAFTA and trade deals," Edwards said.

Obama responded by criticizing Edwards for voting for permanent trade relations with China and struck out at Clinton for saying last year that NAFTA has been boon to the economy. "I think it's been devastating," Obama said.

South Carolina holds its primary Saturday. The two-hour debate was sponsored by the Congressional Black Caucus Institute and CNN.