WASHINGTON

The struggles of the nation's blacks a loyal Democratic voting bloc topped the agenda Thursday as the party's eight presidential candidates gathered for their third primary debate.

The debate at Howard University was scheduled to begin just hours after the Supreme Court ruled against public school programs aimed at achieving racial diversity, a certain topic for the event.

Democratic front-runner Hillary Rodham Clinton said the decision turned its back on the promise of integrated schools that the court laid out 53 years ago in its landmark decision in Brown v. Board of Education.

"As president, I will fight to restore Brown's promise and create an education system where all children have an equal chance to learn and excel together," she said in a statement.

Sen. Barack Obama of Illinois called the ruling "wrong-headed."

It is "but the latest in a string of decisions by this conservative bloc of justices that turn back the clock on decades of advancement and progress in the struggle for equality," he said.

Also scheduled to appear on stage were Sens. Chris Dodd of Connecticut and Joe Biden of Delaware; 2004 vice presidential nominee John Edwards; New Mexico Gov. Bill Richardson; Ohio Rep. Dennis Kucinich and former Alaska Sen. Mike Gravel.

Moderating the debate is Tavis Smiley, who says he wants to steer the conversation to issues raised in his book, "The Covenant with Black America." The 90-minute event was being broadcast live on public television.

The debate is an opportunity for Obama, who got lukewarm reviews from his first two debate performances, to stand out and share a bond with the audience. But he's in a tight contest for the black vote with Clinton, who benefits from goodwill for her husband in the community.

Edwards is trying to make gains. His campaign put out a memo Thursday showing how he is addressing Smiley's 10 covenants, including health care, education, criminal justice, police accountability, housing and voting rights.