Edwards, the party's 2004 vice presidential nominee, depicted Clinton as the embodiment of the political status quo, noting the amounts of money she has taken from interest groups.
"Will she be the person who brings about change in this country?" asked Edwards, whose attacks were the most persistent. "I believe in Santa Claus. I believe in the tooth fairy. But I don't think that's going to happen."
While Clinton vigorously defended herself at times, she seemed unrattled by the attacks, though she stumbled in the final minutes on an immigration question. Mostly, she was content to restate her positions and to scoff at the notion that her election would not represent significant change.
"I have been standing against the Republicans, George Bush and Dick Cheney," she said, "and I will continue to do so, and I think Democrats know that."
Clinton's rockiest moment came when she appeared to endorse states' giving driver's licenses to undocumented immigrants, then backed away from it. Several of the other candidates said they had no idea what her true position was, although only Sens. Christopher J. Dodd of Connecticut and Joseph R. Biden Jr. of Delaware, the latter after the debate, said they were against giving such licenses.
One question that her rivals were eager to discuss during the debate, telecast by MSNBC, was whether Clinton could win a general election.
Polls show more than 40 percent of voters say they have ruled out voting for her next November. At the same time, she is winning hypothetical matchups with various potential Republican nominees, most of whom talk of her as if she already has been nominated.
"Part of the reasons Republicans are so obsessed with you is that's a fight they're very comfortable having," said Obama, who had announced in advance his intention to be more aggressive as a candidate. "What we don't need is another eight years of bickering."
Edwards chimed in, telling Clinton that Republicans "want to run against you."
Finally, New Mexico Gov. Bill Richardson tried to put a stop to the sniping, even as he reminded viewers that governors like himself, not senators like Clinton, get elected president.
"I'm hearing this holier-than-thou attitude toward Sen. Clinton and it's bothering me," he said, "because it's pretty close to personal attacks we don't need."
Clinton is getting nearly 50 percent of the Democratic vote in some national polls and is leading in most of the key early states, though she faces a tough fight with Obama and Edwards in Iowa, site of the first-in-the-nation caucuses on Jan. 3.
For that reason, her rivals looked for every opportunity to weaken her, including discussion of the resolution enacted in the Senate last month labeling Iran's Revolutionary Guard a terrorist organization.
Clinton voted for it. Two of her Democratic presidential rivals, Biden and Dodd, voted against it. All the others said that supporting it was a mistake.
Biden said the resolution had emboldened the Bush administration in moving toward a military confrontation with Iran, raised the price of oil worldwide, and created political instability in Pakistan and Afghanistan.
"If nothing else happens, this was bad policy," Biden said. "All it has done is hurt us."
Said Dodd: "I believe this issue is going to come back to haunt us." Added U.S. Rep. Dennis J. Kucinich of Ohio: "When you say all options are on the table, you are licensing President Bush" to move toward war.
Edwards suggested that Clinton's action was naive at best. "The way you put pressure on this administration is you step up to them and say no," he said. "You give this president an inch and he'll take a mile."
Clinton said she wanted to make sure everyone understood her position on Iran.
"I am not in favor of this rush for war," she said. "But I am also not in favor of doing nothing."
The Senate resolution, she said, called for vigorous diplomacy, including economic sanctions, which she called the right way to try to prevent Iran from acquiring nuclear weapons.
Clinton took heat on the war in Iraq as well, even as she reiterated her measured plan to extricate the United States from that conflict. That plan has not satisfied some voters in the party's antiwar base.
"I will begin to bring our troops home as soon as I'm president," she said.
Obama, who described Clinton as having supported the war before she opposed it, said she was not the right person to undo the Bush policies. The key, he said, is having a president "who has not been one of the coauthors of this engagement in Iraq."
Edwards accused her of wanting to leave combat troops behind to wage combat missions and pointed to her unwillingness to set a timetable for complete withdrawal.
"You have choices, very clear choices," Edwards said. "I will get the troops out in my first year."
Other issues raised during the debate included education, energy policy, natural disasters, immigration, health care, tax policy and Social Security.
Despite the big-city setting, no special attention was given to urban issues by the questioners, Brian Williams and Tim Russert of NBC News.
Perhaps the best line of the night - in terms of the reception from the pro-Democratic crowd at Drexel's Main Building Auditorium - came from Biden, who has made no secret of his contempt for the idea that Republican Rudy Giuliani might get elected president.
"All he says is a noun and a verb and 9/11; there's nothing else," Biden said. "He is genuinely not qualified to be president."
Contact senior writer Larry Eichel at 215-854-2415 or email@example.com.