In a sign of just how tense and close the race for the Democratic presidential nomination has become, Illinois Senator Barack Obama, who has made a point of saying he wishes to avoid the politics of personal attacks, went on the offensive on Monday during a sniping Democratic debate in South Carolina.

Obama, who has not won a contest since taking the Iowa caucus on January 3, traded barbs with leading candidate Senator Hillary Clinton during the televised debate Monday, during which Clinton accused Obama of consorting with slum lords and praising Republican President Ronald Reagan. The Illinois senator shot back that his opponent's husband, former President Bill Clinton, had distorted his record, and that he felt like he was running against not one, but two Clintons.

Clinton landed one of the hardest jabs during the event at the Palace Theatre in Myrtle Beach, South Carolina — the state that will hold its Democratic primary on Saturday — telling Obama, "You know, Senator Obama, it is very difficult having a straight-up debate with you, because you never take responsibility for any vote, and that has been a pattern." It was one of several points during the night when the two questioned each other's honesty, attempting to portray the other as a candidate whose word could not be counted on by voters.

Clinton's comment drew boos from the crowd, and brought out a spark of frustration and a tinge of anger in Obama, who has made a point of not engaging his opponents in negative campaigning. Meanwhile, former Senator John Edwards, trying to portray Clinton and Obama as focusing more on their jibes than the issues, worked hard to get some screen time, a telling sign of a campaign that has failed to catch fire or produce any wins to date. After several bouts of Clinton and Obama talking heatedly over each other, Edwards joked, "There's a third person in this debate."

The second-to-last debate of the primary season found Obama and Clinton pulling out some nasty accusations about each other, with Clinton saying that while she was fighting against the bad ideas of Republican administrations, Obama was "practicing law and representing [his] contributor [Tony] Rezko in his slum-landlord business in inner-city Chicago." She was referring to longtime Obama fundraiser Tony Rezko, who was indicted last fall on federal charges of business fraud and influence peddling. As an attorney in Chicago, Obama worked on behalf of some of Rezko's housing developments. According to The New York Times, Obama donated more than $40,000 in campaign contributions linked to Rezko to charity on Saturday.

While Edwards tried to stay out of the battle by saying that none of the personal bickering would help children get health care or solve any of the country's problems, he did get a shot in at Obama, slamming his opponent for voting "present" on bills — rather than "yea" or "nay" — 130 times while he was an Illinois state senator. The back-and-forth resulted in an awkward moment in which Obama had to explain the complicated political tactics of voting "present" in the Illinois Legislature, which seemed to somewhat undercut his long-touted campaign theme of his not being an entrenched part of the typical political machine.

"What if I had just not shown up to vote on things that really mattered to this country?" Edwards asked. "It would have been safe for me politically. It would have been the careful and cautious thing to do, but I have a responsibility to take a position."

Obama, who has not taken the bait when attacked in the past, appeared to lose his patience with Clinton at times, snapping that she was on the board of directors of Wal-Mart while he was working as a community organizer in Chicago. Obama also tore into Bill Clinton, saying the former commander in chief had repeatedly distorted his record. In her continuing attempt to make it clear that she is the one calling the shots in her campaign, Clinton responded, "I'm here ... not my husband." Obama was quick to reply, "I can't tell who I'm running against sometimes."

In front of a mostly black audience, the one issue that didn't really come up during the debate, held on the national holiday honoring the late Dr. Martin Luther King Jr., was race. Obama and Clinton traded harsh words two weeks ago after Clinton made a comment regarding President Lyndon Johnson's pivotal role in passing civil-rights legislation, which the Obama campaign said was a slight to Dr. King.

In one of the debate's lighter moments, Obama was asked about the widely quoted comment from author Toni Morrison that Bill Clinton was the country's first "black" president. "I think Bill Clinton did have an enormous affinity with the African-American community," Obama said, adding, "I would have to investigate more of Bill's dancing abilities and some of this other stuff before I accurately judge whether he was, in fact, a brother." Hillary Clinton, currently trailing Obama in the polls in South Carolina, where the black vote is expected to help secure him a victory, shot back, "I am sure that can be arranged."