WASHINGTON — Clear differences are emerging among the top three Democratic presidential candidates on security, with Senator Clinton breaking with her rivals in affirming the war on terrorism and declaring that America is safer now than it was six years ago.

In a presidential debate that featured sharp clashes among the candidates for the first time, Mrs. Clinton set herself apart from both John Edwards and Senator Obama over the fight against terrorism. Mr. Edwards, a former North Carolina senator who has staked out a fervent anti-war position, said he rejected the use of the phrase “war on terror,” which he derided as a “bumper sticker” and a “political slogan.”

Mr. Obama, the first-term Illinois senator, said that even though the country has not suffered another major terrorist attack since September 11, 2001, “we are living in a more dangerous world, not a less dangerous world, partly as a consequence of this president’s actions.”

Mrs. Clinton distanced herself from each statement. “No, I do not,” she said when asked if she agreed with Mr. Edwards. “I am a senator from New York. I have lived with the aftermath of 9/11, and I have seen firsthand the terrible damage that can be inflicted on our country by a small band of terrorists who are intent on foisting their way of life and using suicide bombers and suicidal people to carry out their agenda.

“And I believe we are safer than we were,” she added. “We are not yet safe enough.”

It was a rare move for the former first lady, who used much of her speaking time in the two-hour debate trying to downplay divisions among the Democrats while heaping criticism on President Bush.

The debate, broadcast live on CNN from St. Anselm College in Manchester, was the second involving all eight Democratic presidential candidates and the first in New Hampshire, site of a key early primary.

It focused heavily on foreign policy, as several of the candidates said the next president would need to restore America’s moral authority in the world, which they said was tarnished by the Bush administration. They aired differences on Iraq, Iran, and how to respond to the humanitarian crisis in Darfur. Senator Biden of Delaware pleaded for swift action, including the possible use of military force, to stop the violence. Governor Richardson of New Mexico, a former ambassador to the United Nations, urged putting pressure on China to influence the Sudanese government. Mr. Richardson suggested threatening to boycott the 2008 Olympics in Beijing in a move that would be reminiscent of President Carter’s decision to scrap American participation in the 1980 Olympics in Moscow over the Soviet Union’s invasion of Afghanistan.

Senator Dodd of Connecticut shot down the idea, saying it “goes too far.”

The debate also featured a confrontation on Iraq, with Mr. Edwards criticizing Mrs. Clinton and Mr. Obama for not speaking out more loudly when they cast their votes last month against an emergency funding bill that did not include a timeline for American troop withdrawal.

“I think it’s the difference between leading and following,” Mr. Edwards said. He did not at first mention the two senators by name, but after prodding from moderator Wolf Blitzer — and an audible laugh from Mrs. Clinton — he specified her and Mr. Obama.

The Illinois senator responded sharply.

“I think it is important to lead,” Mr. Obama said. “John, I think the fact is I opposed this war from the start, so you’re about four-and-a-half years late on leadership on this issue.”

Mr. Edwards, who has called his 2002 vote for the war a mistake, later acknowledged as much. “He was right. I was wrong,” he said.

The two also tangled over health care, with Mr. Edwards criticizing the plan Mr. Obama announced last week as not achieving “truly universal” coverage via a mandate.

Mrs. Clinton, positioned between Messrs. Edwards and Obama at the center of the stage, appeared to enjoy the exchanges. She laughed at several points during the debate, even as Mr. Edwards sought to voice his differences with her stance on the war.

She tried her best to deflect much of the criticism onto the Bush administration, saying of Iraq, “This is George Bush’s war.”

“The differences among us are minor,” she said, referring to her fellow Democrats on the stage. “The difference between us and the Republicans are major.”

That drew disagreement from two of the long shot candidates in the debate, particularly a former Alaska senator, Michael Gravel, who said the war was “facilitated” by the Democrats. “Sure, it’s George Bush’s war,” he said. “But it’s the Democrats’ war also.”

About the only thing Mr. Gravel and Mrs. Clinton agreed on was how to use her husband. Mr. Gravel, who was first asked the question usually reserved for Mrs. Clinton, said he would dispatch President Clinton as a “roving ambassador,” which is how the former first lady described her plans.

Mrs. Clinton was also forced to answer for her husband’s “don’t ask, don’t tell” policy toward gays in the military. She supports getting rid of it and allowing gays to serve openly, but she refused to call it a mistake, saying it was a “transition policy.”

The Republican candidates for president will take the same stage tomorrow night for their third debate of the primary campaign.