But on Friday, they were more than happy to appear for their collective debut, which was carefully choreographed by the DNC staff. Supporters of each candidate were allowed no more than 100 signs in the auditorium. A candidate could play no more than 30 seconds of music to accompany his or her entrance and exit, barely enough time for the Bachman-Turner Overdrive clip to reach the lyrics "You Ain't Seen Nothing Yet" as Clinton left the stage.

Edwards, the party's 2004 vice presidential nominee, described an America in which children are going to bed hungry, or crying themselves to sleep over a parent's lost job. Young people are turning down college acceptance letters because they can't afford to go, he said, while every week another parent learns of the death of a child in Iraq.

"It doesn't have to be that way," Edwards repeated in his somber speech. "Silence is betrayal."

Clinton took the stage in a fighting mood, promising the party base that she's "in to win" and that, as a veteran of the national battlefield, she knows how to do so.

"I know a thing or two about winning campaigns," she said. "When our party and our candidates are attacked, we have to stand up and fight back."

Clinton soldiered on through a mild spate of heckling, drowning one protester's cries to "Bring them home!" in a torrent of applause for her promise to end the war in January 2009 if Congress hasn't already done so.

When it was his turn, Obama mildly reminded the crowd that he opposed the invasion of Iraq "publicly and frequently" beforehand. He decried what he said is a bitter cynicism in American politics, one that "makes us afraid to say what we believe. It makes our politics small and timid."

"Democrats, this is not a game," he said. "This can't be about who digs up more skeletons on who. . . . We owe it to the American people to do more than that."

Democrats should deliver something more, he said.

"That's what we offer the American people. Hope," he said. "We've had a lot of plans, Democrats. What we've had a shortage of is hope . . . I'm calling on you to hope."

Later in the day, Obama spoke to a raucous rally of college students at the student center at George Mason University, a commuter school in the Washington suburb of Fairfax, Va.

The event, organized by a national student group promoting Obama's presidential candidacy, provided a preview of a campaign expected to kick off Feb. 10 when Obama plans to officially launch his candidacy. Students filled a three-level atrium, cheering, holding up Obama placards, waving copies of his latest best-selling book, and rushing for the chance to shake his hand as he departed.