HANOVER, New Hampshire (Reuters) - Democratic presidential candidates pounced on rival Hillary Clinton for her positions on Iraq and Iran in a debate on Wednesday as they sought to undercut her status as the campaign front-runner.

Democratic presidential candidates (L-R) U.S. Senator Barack Obama (D-IL), former U.S. Senator John Edwards (D-NC), U.S. Representative Dennis Kucinich, (D-OH), and U.S. Senator Hillary Clinton (D-NY) pose for photographers before their debate at Dartmouth College in Hanover, New Hampshire September 26, 2007. REUTERS/Lisa Hornak

Former North Carolina Sen. John Edwards, a distant third place in most national polls and needing a breakthrough performance, led the attack against Clinton on the campus at Dartmouth College.

With the Democratic left-wing demanding a hasty U.S. timetable out of Iraq, Edwards criticized the New York senator for not ruling out that U.S. troops might engage in some combat missions in Iraq if she were to win the 2008 election.

“To me that’s a continuation of the war,” Edwards said. “Combat missions mean that the war is continuing. I believe the war needs to be brought to an end.”

Edwards’ broadside put Clinton on the defensive at a time when she is enjoying a comfortable lead in opinion polls and trying to appear above the fray. But there was no sign that the debate would prompt a major shake-up in the Democratic field.

“There may be a continuing counter-terrorism mission,” she said, while adding that “the vast majority” of American troops would be out of Iraq by the end of her prospective first term in 2013.

The cross-fire on the campus of Dartmouth College came at the first debate of the critical autumn season leading up to the early voting contests in January ahead of the November 2008 election to replace President George W. Bush.

Iraq was a dominant theme of the debate as Democrats seek a way to force Bush to change his war strategy, which may leave as many as 100,000 troops there by the time the next president is inaugurated in January 2009.

IRAN’S REVOLUTIONARY GUARD

Iran occupied plenty of attention as well. Washington accuses Iran of trying to develop a nuclear bomb and supplying weapons to Iraqi guerrillas fighting the U.S. forces. Tehran denies the charges.

Edwards criticized Clinton for voting earlier in the day in Washington to approve a nonbinding motion calling on the State Department to designate Iran’s Revolutionary Guard as “a foreign terrorist organization,” which Edwards said was a potential first step toward war against Iran.

“I have no intention of giving George Bush the authority to take the first step on a road to war with Iran,” Edwards said, pointedly mentioning that two other candidates on stage, Delaware Sen. Joe Biden and Connecticut Sen. Christopher Dodd, had voted against the measure.

Long-shot candidate Mike Gravel jumped on Clinton as well, saying, “I am ashamed of you, Hillary, for voting for it.”

After a loud laugh at the often-comical Gravel, Clinton defended her vote.

She said it would allow the U.S. government to designate the Revolutionary Guard “as a terrorist organization which gives us the options to be able to impose sanctions on the primary leaders to try to begin to put some teeth into all this talk about dealing with Iran.”

OBAMA HOLDS HIS PUNCHES

Illinois Sen. Barack Obama, in second place in the polls despite leading in fund-raising, held his punches against Clinton.

He reiterated his position that he would engage in direct talks with Iran, a pledge Clinton has said shows Obama is too inexperienced to be president.

“We’ve got to talk to our enemies and not just our friends,” Obama said.

Biden suggested Clinton’s experience as first lady in the administration of her husband, former President Bill Clinton, when she tried unsuccessfully in the 1990s to reform health care, would hamper her effectiveness as a U.S. president.

“I’m not suggesting it’s Hillary’s fault. I think it’s a reality that it’s more difficult, because there’s a lot of very good things that come with all the great things that President Clinton did, but there’s also a lot of the old stuff that comes back,” Biden said.

As Clinton fixed a chilly stare on him, Biden hurriedly added: “When I say old stuff, I’m referring to policy, policy.”