Former Sen. John Edwards of North Carolina, a South Carolina native, used the occasion to stress his plans to fight poverty, calling that struggle "the cause of my life." He also reprised his theme of an America divided into haves and have-nots, a split he defined in large part by race.
"The truth is that slavery followed by segregation followed by discrimination has had an impact that still is alive and well in America, and it goes through every single part of American life," Edwards said. "We still have two public school systems in America. These two Americas that I've talked about in the past -- man, they are out there thriving."
Two candidates -- Rep. Dennis J. Kucinich of Ohio and former Alaska Sen. Mike Gravel -- promised a large shift of funding from the military to public schools.
"I'm ready to see at least a 15% reduction in that bloated Pentagon budget," Kucinich said. "Stop funding war. Start funding education. That's where we get the money."
"Dennis, you're a little too modest on that," Gravel said. "I think we can cut a little more than 15% -- very much so."
A question on the high rate of HIV infection among African American teens triggered the liveliest exchange when Sen. Joseph R. Biden Jr. of Delaware said: "I spent last summer going through the black sections of my town, holding rallies in parks, trying to get black men to understand it is not unmanly to wear a condom, getting women to understand they can say no, getting people in the position where testing matters. I got tested for AIDS. I know Barack got tested for AIDS."
At that, Obama shot Biden a you've-got-to-be-kidding glance. A television camera caught the Rev. Al Sharpton in the audience looking appalled. (In January, Biden nearly derailed his campaign by referring to Obama as the first "clean" and "articulate" African American to seek the presidency.)
When the laughter died down and it was his turn to speak, Obama countered: "I want to make clear, I got tested with Michelle.... I don't want any confusion here about what's going on."
Obama and his wife, Michelle, both took HIV tests on a visit last year to Kenya, a gesture meant to show there was no stigma in being screened for the virus.
Most of the candidates agreed that the government must spend more on AIDS research and treatment.
Clinton suggested racial prejudice was to blame for the outsize impact of HIV on African Americans. If AIDS "was the leading cause of death of white women between the age of 25 and 34, there would be an outraged outcry in this country," she said.
