PHILADELPHIA, Pennsylvania (CNN) -- Sen. Hillary Clinton's rivals attempted to shake up the race for the Democratic presidential nomination Tuesday night by attacking the former first lady's credibility, consistency and electability.
Former Sen. John Edwards wasn't the only Democrat to go after Sen. Hillary Clinton at Tuesday's debate.
The Democratic presidential candidates tried to chip away at Clinton's front-runner status in a debate at Drexel University, a matchup that Sen. Barack Obama of Illinois joked was "the most hyped fight since Rocky fought Apollo Creed."
Obama vowed going into the debate that he was going to sharpen his criticism of Clinton and quickly went on the attack.
"Sen. Clinton in her campaign, I think, has been for NAFTA, and now she is against it," Obama said, referring to the North American Free Trade Agreement.
"She has taken one position on torture several months ago and most recently has taken a different position. She voted for a war, to authorize sending troops into Iraq, and then later said this was a war for diplomacy." Watch Obama go on the offensive »
Obama added, "Now, that may be politically savvy, but I don't think that it offers the clear contrast that we need."
The Democrats' seventh debate marked the first face-off since they tangled last month at Dartmouth College in New Hampshire. While not the knock-down, drag-out many had predicted, it nevertheless was pointed.
Former Sen. John Edwards of North Carolina wielded the sharpest blade, standing by his accusation that the senator from New York engages in double talk.
"Sen. Clinton says that she believes she can be the candidate for change, but she defends a system that is broken in Washington, D.C. She says she will end the war, but she continues to say she will keep combat troops in Iraq and continue combat missions in Iraq," Edwards said.
Edwards is trailing Clinton and Obama in national polls but is neck and neck with them in Iowa, scene of the election season's first caucus.
Sen. Christopher Dodd, D-Connecticut, also raised the issue of whether Clinton was electable.
"Whether it's fair or not fair, the fact of the matter is that my colleague from New York, Sen. Clinton, there are 50 percent of the American public that say they're not going to vote for her," Dodd said.
While at times exhibiting an edge in her responses, Clinton refused to engage her primary opponents, aiming her fire instead at President Bush
"On every issue from health care for children to an energy policy that puts us on the right track to deal with climate change and make us more secure I've been standing against George Bush and Dick Cheney, and I will continue to do so, and I think Democrats know that," she said.
During the debate, Clinton sidestepped sticky issues such as whether illegal immigrants should be given driver's licenses or how she would fix Social Security.
Clinton said New York Gov. Eliot Spitzer's controversial plan to give driver's licenses to illegal immigrants "makes a lot of sense," but she stopped short of endorsing the proposal.
That response prompted Edwards to criticize Clinton for being "inconsistent."
"Unless I missed something, Sen. Clinton said two different things in the course of about two minutes just a few minutes ago," Edwards said. "America is looking for a president who will say the same thing, who will be consistent, who will be straight with them. Because what we've had for seven years is double talk from Bush and from Cheney, and I think America deserves us to be straight."
Clinton also refused to pledge that Iran would not develop a nuclear bomb under her watch if elected president, but she said, "I will do everything I can to prevent Iran from developing a nuclear bomb."
She added, "I have stood against George Bush and his failed policies. They want to continue the war in Iraq. I want to end it. The Republicans are waving their sabers and talking about going after Iran. I want to prevent a rush to war."
The attacks on Clinton were so great that at one point New Mexico Gov. Bill Richardson came to her defense.
"I'm hearing this holier than thou attitude toward Sen. Clinton that -- it's bothering me because it's pretty close to personal attacks that we don't need," Richardson said.
"Yes, we need to point out our differences ... but I think it's important that we save the ammunition for the Republicans." E-mail to a friend
CNN's Candy Crowley and Steve Brusk contributed to this report.