DETROIT -- Democratic presidential contenders attacked President Bush's postwar policy in Iraq with gusto in a their fifth campaign debate Sunday night, accusing him of failing to protect the troops, seek international help or level with the American people.

"We cannot afford to play Bush roulette ... with the lives of American troops," said the Rev. Al Sharpton, sharing a stage with eight other White House hopefuls.

Over 90 contentious minutes, the Democratic hopefuls also attacked one another sharply on Iraq.

Sen. Joe Lieberman, an early and aggressive proponent of the war, said retired Gen. Wesley Clark had "six different positions on whether going to war was a good idea. It took him four days to decide" his position on Bush's recent call for $87 billion in aid to Iraq and Afghanistan, the Connecticut senator added.

Clark said he had been "entirely consistent" in opposing the war.

Lieberman also accused several of his rivals of being inconsistent by voting to support the war yet opposing Bush's request for postwar funding.

Kerry rebutted that charge by invoking his service in the Vietnam War. Addressing Lieberman, he said he had "seared into me an experience you don't have, and that is being one of the troops on the front line when the policy has gone wrong."

The Massachusetts senator wasn't the only one to invoke his military experience. Clark, a retired four-star general who led the NATO campaign in Bosnia, did likewise.

That alone was noteworthy in a debate among Democrats. Public opinion has long shown that voters prefer Republicans to Democrats on defense issues -- something the current crop of contenders is hoping to change.

The Congressional Black Caucus Institute and the Fox News Channel sponsored the debate.

It was their fifth debate in seven weeks.

The first balloting of the primary race takes place in less than three months -- the Iowa caucuses are slated for Jan. 19, the New Hampshire primary follows eight days later. Seven other states will vote on Feb. 3, in the first multi-contest of the nominating season.

The war also prompted a challenge from Rep. Dennis Kucinich of Ohio to former Vermont Gov. Howard Dean. Kucinich accused Dean of running a television commercial that falsely says he was the only contender to oppose the war in Iraq.

"Why forfeit the public trust? Why can't you just admit you made a mistake and take down the ad?" said Kucinich, who voted against the war and noted that Sharpton and former Sen. Carol Moseley Braun also opposed it.

Dean brushed aside the challenge, saying, "I don't think my ad is inaccurate at all."

By prior arrangement, the second half of the debate focused on domestic policy, and the Democrats seemed eager to criticize one another on those topics, as well.

Kerry sharply attacked Dean's proposal to repeal all of Bush's tax cuts. He said that would mean middle-class taxpayers would lose a child tax credit, as well as resume paying a marriage penalty again. Referring to an Iowa family, he said the impact of Dean's cuts would be a $2,178 increase in taxes.

Kerry favors repealing the portion of Bush's tax cuts that benefit the wealthy, but not the balance of the reductions he won from Congress.

Given the chance to speak moments later, Dean scorned Kerry. "If you're going to defend the president's tax cuts and you're going to defend the war, I frankly don't think we can beat Bush by being Bush-lite."