WASHINGTON — Democrats Hillary Clinton and Barack Obama insisted yesterday they don't want to turn their historic campaign into a clash over race or gender, blaming their staffs and supporters for a recent war of words over race.

"We both have exuberant and sometimes uncontrollable supporters. ... We need to get this campaign where it should be," Clinton said at the outset of a two-hour debate.

"Our supporters, our staff, get overzealous," Obama added. "They start saying things that I would not say, and it is my responsibility to make sure that we're setting a clear tone in our campaign."

Their words of contrition — or blame — came after days of escalated charges and countercharges between the two camps over whether Clinton played on racial divisions or somehow besmirched the late Rev. Martin Luther King Jr. by noting that it took President Lyndon Johnson to push King's dream of civil rights into law.

But their running exchange reflected more than just that — it was also the unique drama of a black man and a white woman locked in a razor-close contest for a major party presidential nomination, with each side ready to capitalize on the slightest hint of a slight.

Clinton, the New York senator whose supporters charged that she was the subject of sexist attacks last fall when she came under fire from male rivals and debate moderators, said yesterday "neither race nor gender should be a part of this campaign."

She declined to say she would shut out a prominent supporter for making an apparent reference to Obama's admitted drug use as a teen, despite her statement over the weekend that she would fire any staffer who attacked Obama.

She said that the supporter "put out a statement saying what he was trying to say and what he thought he had said. We accept him on his word on that."

"Race is a factor in our society," said Obama, a senator from Illinois whose mother is a white woman from Kansas and father is a black man from Kenya.

But he said that his victory in caucuses in predominantly white Iowa "is a testimony to the fact that the American public is willing to judge people on the basis of who can best deliver the kinds of changes that they're so desperately looking for, and that's the kind of movement that we want to build all across the country."

Former North Carolina Sen. John Edwards, a Southern white man, was almost rendered a bystander, seated beside Clinton and Obama on the debate stage.

"The only thing I would add is I had the perspective of living in the South, including at a time when there was segregation in the South, and I feel an enormous personal responsibility to continue to move forward," Edwards said.

The apparent truce extended beyond the debate, at least for the evening: None of the campaigns sent out e-mails criticizing one another, a first. Normally, one campaign fires off a blast within seconds after a rival finishes saying something.

The debate came four days before Democratic and Republican caucuses in Nevada on Saturday.

Polls suggest a close three-way race heading into the Democratic caucuses, but Nevada has never held a large-scale presidential caucus before, so it was anybody's guess who might win.

Obama did have one big edge, however. He won the backing last week of the 60,000-member culinary workers union, which could provide a wealth of organizational muscle in the meetings.

As the candidates took the stage, lawyers took to Nevada courts to fight about the campaign.

In one case, Clinton supporters urged Nevada courts to order changes in rules that will allow caucuses in Las Vegas strip hotels — arguing that hotel workers will have access to the caucuses not enjoyed by other voters.

Clinton didn't object when the caucus rules were adopted last spring. But after the culinary union, which represents those hotel and resort workers, endorsed Obama, Clinton supporters filed the lawsuit.

In the other case, the Nevada Supreme Court decided an hour before the debate that MSNBC had the right to exclude Rep. Dennis Kucinich of Ohio.

Earlier, a state judge ordered the network to include Kucinich, saying its earlier invitation amounted to a binding contract that couldn't be broken just because he finished dismally in Iowa and New Hampshire voting.