All four of the incumbent senators in the field – Hillary Rodham Clinton of New York, Barack Obama of Illinois, Joseph Biden of Delaware and Christopher Dodd of Connecticut – voted earlier in the day for a Democratic plan to force the start of troop withdrawals from Iraq by Oct. 1.

But some of the more strident anti-war candidates were focused on the vote more than four years ago that permitted President Bush to launch that war. At the time, Biden, Clinton, Dodd and former Sen. John Edwards of North Carolina voted to authorize the use of force.

Ohio Rep. Dennis Kucinich, whose long-shot campaign is driven by his opposition to the conflict, said the 2002 Iraq vote should be critical to voters. “This isn't 'American Idol' here. We're choosing a president. And we have to look at the audition that occurred – when my good friends were called upon to make a decision and then made the wrong decision.”

Asked to cite mistakes they had made, Clinton mentioned “believing the president when he said he would go to the United Nations and put inspectors into Iraq to determine whether they had WMD.” She called that vote “a sincere vote based on the information available to me,” adding, “If I knew then what I now know, I would not have voted that way.”

Biden, Dodd and Edwards also recanted their pro-war votes, with Biden saying his biggest mistake was “overestimating the competence of this administration and underestimating the arrogance.”

Edwards, who repeatedly apologized for his vote, took Clinton to task for not being sufficiently contrite, calling it “a question of conscience.” He added, “I think it's important to be straightforward and honest.”

Also participating in the debate – which came a full 264 days before the first vote that counts is cast in Iowa – were Gov. Bill Richardson of New Mexico and former Sen. Mike Gravel of Alaska. The candidates squared off in Martin Luther King Jr. Auditorium at South Carolina State University, the state's first black college.

In addition to the war, the candidates were asked about a variety of issues and were in general agreement on many: the need to expand health care and control costs, support for abortion rights and keeping people with mental illness from obtaining guns, such as the man who killed 32 people and himself at Virginia Tech.

Some of the questions clearly caused candidates discomfort.

Edwards was stung when asked about billing his campaign for two $400 haircuts this year, which had annoyed some of his contributors and made him fodder for late-night comedians.

“That was a mistake, which we've remedied. It was simply a mistake,” he said, quickly adding that the question is “whether I live a privileged and blessed lifestyle now, (and) the answer to that's yes. A lot of us do. But it's not where I come from. And I've not forgotten where I come from.”

A few minutes later, Richardson seemed to take a shot at Edwards while trying to explain why he had been slow to demand the removal of Alberto Gonzales as attorney general. The governor conceded that it was because Gonzales, like Richardson, is Latino. But he said: “I think the American people want candor. They don't want blow-dried candidates with perfection.”

The debate, sponsored and aired by MSNBC, had moments both humorous and odd.

Biden got the night's biggest laugh when moderator Brian Williams of NBC News asked about his famed “verbosity” and proclivity for verbal gaffes. When Williams finished his 61-word question asking whether Biden could assure voters he had the discipline needed on the world stage, Biden simply said, “Yes.” He then did something rarely seen in his long Senate career – he remained silent.

Gravel supplied some of the strangest comments during the debate. He grumpily dissented on most views expressed by the others and, at one point, said of the other candidates, “They frighten me.” Asked to be specific, he cited “the top tier,” only to add Biden to the list because “you have a certain arrogance.”

The debate was the first real opportunity for the second-tier candidates to try to make inroads against the three front-runners: Clinton, Obama and Edwards.

But most analysts' immediate assessment was that the debate didn't do much to alter the campaign's dynamics, in part because it's so early in the process.

While there were no obvious gaffes, Obama seemed to stumble during the latter half of the debate. He had to be prodded to list Israel as an important U.S. ally. And when the candidates were asked how they would respond if al-Qaeda attacked two major U.S. cities, he was the only one who didn't say he would retaliate or strike back. Instead, Obama talked of managing an effective emergency response and said he would make sure he didn't “alienate the world community.”

His aides later said they thought the senator had misheard the question on how he would respond to a terrorist attack.

Obama also allowed himself to be drawn into a spat over Iran with two long-shot candidates, Kucinich and Gravel, appearing exasperated in the exchange.