The Democratic race for president is heating up with only one week left before the Iowa caucuses.

Howard Dean (search) was assailed for his race record Sunday by his rivals for the presidential nomination in the last Democratic debate before the caucuses.

The various Democratic hopefuls took turns chastising Dean, a former governor of mostly white Vermont, during the Iowa Brown and Black Presidential Forum (search), a two-hour debate focusing on issues important to blacks and Hispanics. It was the third debate in Iowa in eight days.

Civil rights activist Al Sharpton forced Dean to acknowledge that no blacks or Hispanics served in his cabinet during 12 years as governor.

"While I respect the fact you brought race into this campaign, you ought to talk freely and openly about whether you went out of the box to try to do something about race in your home state and have experience with working with blacks and browns at peer level, not as just friends you might have had in college," Sharpton said.

Dean responded, "I will take a back seat to no one in my commitment to civil rights in the United States of America."

Recent polling shows Dean and Missouri Rep. Dick Gephardt (search) in a close race in the state, with Sen. John Kerry (search) of Massachusetts and Sen. John Edwards (search) of North Carolina trailing. The outcome will begin the winnowing process in the race for the nomination.

Dean hopes for a victory to validate his claim as campaign front-runner. Gephardt's aides say he must win. Kerry and Edwards hope for strong finishes to sustain their campaigns in New Hampshire, whose primary follows Iowa by eight days.

"We're past all this preliminary stuff. It's time to choose a president," Edwards said.

Dean revealed some clues to his plan to redistribute the burden for paying taxes away from the middle class. He said he's examining a way to increase corporate taxes and perhaps cut payroll — or Social Security — taxes.

He said his first priority would be to balance the budget, which will require repealing all of President Bush's tax cuts. Gephardt challenged him about whether he could cut payroll taxes without harming Social Security.

"I think cutting payroll taxes is not a bad idea," Dean said. "It's certainly something we're going to look at. Under no circumstances will we take the money to cut payroll taxes out of the Social Security trust fund. That would be absurd."

Rep. Dennis Kucinich (search) of Ohio jumped into the fray against Dean, criticizing the front-runner for saying he could balance the budget without cutting Pentagon spending.

Kerry said Dean was trying to have it both ways on the Iraq war, speaking out as an opponent but having spoken in support of congressional legislation in fall 2002 that would have given Bush the authority to use force in Iraq, so long as he notified Congress in advance.

Dean also took some heat from members of the audience.

Dale Ungerer, a 66-year-old retiree from Hawkeye, Iowa, made Dean show a flash of his much-discussed temper after he lectured the candidate for nearly three minutes near the end of the forum.

Ungerer accused Dean and other Democratic presidential hopefuls of dividing the country by bashing Bush instead of outlining their own plans and showing respect for authority.

"Please tone down the garbage, the mean mouthing, the tearing down of your neighbor and being so pompous," Ungerer told Dean. "You should help your neighbor and not tear him down."

State senator Ken Cheuvront of Arizona said he's tired of the Dean attacks. A member of the centrist Democratic Leadership Council, Cheuvront said after the debate that he has decided to endorse Dean because of all the criticism. "It's starting to look petty," he said. "He's the only viable candidate who can win, who has the money to beat Bush."

Democratic strategist Donna Brazile said Dean's record is fair play for rivals who are mad about his rise, but she thinks Sharpton's attacks caught him off guard.

"But I also think that was a low blow to attack him on his Cabinet, the people he chose to put around him versus his policies," she said.

Racial politics have not been prominent in the snow-white confines of Iowa and New Hampshire. But the primary contest moves to more diverse states beginning on Feb. 3, including South Carolina, where nearly half the voters are expected to be minorities, and Sharpton is looking to make a mark on the race.

Dean initially denied Sharpton's accusation that he didn't have one Hispanic or black holding a senior policy position as governor, saying he had "a senior member of my staff on my fifth floor."

Sharpton said he was asking about the Cabinet, which has a small number of members.

"No, we did not," conceded Dean, whose state has a population that is nearly 98 percent white.

Former Sen. Carol Moseley Braun (search) chastised Sharpton for instigating a "racial screaming match." Sharpton responded that he just wants Dean to be held accountable for his record.

Moments later, Dean noted that he has the endorsements of more members of the Congressional Black Caucus and the Congressional Hispanic Caucus than any other presidential hopeful.

But Sharpton ridiculed that, saying, "I think you only need co-signers if your credit is bad."

For much of the evening, it seemed that a candidate's place in the polls dictated how often and sharply he or she was attacked.

"I was beginning to hope someone would attack me," said Sen. Joe Lieberman (search). No one did. The Connecticut senator is not competing in the caucuses, and lags in the New Hampshire polling.

The Associated Press contributed to this report.