Like combat troops crossing from Kuwait into Iraq, the campaigns of the nine Democrats who are seeking their party's 2004 presidential nomination are about to enter the fog of war.

By its nature, war is unpredictable, and that means the campaigns will be operating for the next days or weeks with more than the usual uncertainty that surrounds such endeavors. But while unknowable, what happens next in Iraq will almost certainly affect domestic politics and the competition among the Democrats seeking the right to challenge President Bush.

As the U.S. attack on Iraq began, spokesmen for most of the campaigns said they were planning no changes in the candidates' schedules or other campaign activities, although they stressed this could change depending on developments. Shortly thereafter, Sen. John Edwards (N.C.) became the first to implement what several campaigns described as a "day-by-day" or "case-by-case" policy.

He announced yesterday that he was canceling a trip to New Hampshire set for today and instead would visit with families near Fort Bragg, home of the 82nd Airborne Division, in his home state.

There was also a discernible impact on the Democrats' campaign rhetoric, with most issuing statements of strong support for U.S. troops in the field while muting their criticism of Bush.

"This is back to commander-in-chief time," said an aide to one of the Democratic hopefuls. "This is about the United States of America and the safety of our troops. It's not a time for equivocations."

Rep. Richard A. Gephardt (Mo.) said, "Nobody wishes for war. But we must face the challenge of terrorism head on and I support our commander in chief and the American military at this critical time in that struggle."

Sen. Bob Graham (Fla.) said: "At a time like this, all Americans must come together to support our commander in chief and our men and women in uniform."

"My prayers are with our troops, their families and our commander in chief," Edwards said.

Appearing on CNN shortly after the first bombs fell on Baghdad, Sen. Joseph I. Lieberman (Conn.) said, "Tonight is one of those nights, I think, in which we're all standing shoulder-to-shoulder. President Bush is a Republican, I'm a Democrat . . . but tonight there's not an inch of distance between us."

Robert Gibbs, press secretary for Sen. John F. Kerry (Mass.), said that as a decorated Vietnam War veteran, Kerry's "thoughts and prayers are first with the men and women who are in harm's way. I think everyone understands this is a time for Americans to come together and think about our troops."

Among the leading Democratic contenders, former Vermont governor Howard Dean has carved out the strongest antiwar stance, becoming a rallying point for many of his party's most fervent opponents of Bush's policy in Iraq. Joe Trippi, Dean's campaign manager, said Dean has made it clear that he will support U.S. troops but continue to criticize Bush's policies.

"We stand by the troops and we stand against the policy. We don't think those are inconsistent at all," Trippi said.

Implementing that approach, Dean told the Reuters news service that the onset of fighting in Iraq "calls for a change in how you campaign. I'm going to say what I think . . . but I certainly want to make clear that I am going to support the troops and then I'm going to campaign without criticizing the president by name."

Another antiwar Democrat, Al Sharpton, said he will "continue to openly question the president's policies" and will continue to participate in peace demonstrations such as a march scheduled for this weekend in New York. But Sharpton recalled that during the Vietnam War, many returning combat veterans felt under attack by the antiwar movement at home.

"We've got to be respectful of the troops while we criticize the president's policies," Sharpton said.

Two other Democratic contenders also suggested no let-up in their criticism of Bush. Rep. Dennis J. Kucinich (Ohio) issued a statement saying he was praying "for the safe return of our troops," but he said in a telephone interview yesterday, "I'm going to step up the challenge to an international policy which had brought us an illegal war and which will bring us more war."

Former Illinois senator and ambassador to New Zealand Carol Moseley Braun said she, too, was praying for the troops, but added, "I think it's awful that this president has put people in harm's way in this way. I'm very disappointed that he could not see the wisdom of choosing peace."

While developments in Iraq could affect some political events at home and the public schedules of the candidates, presidential politics will not be suspended during the fighting. "There's a lot of behind-the-scenes work taking place in this first quarter," said an aide to one of the Democrats. "All the quiet behind-the-scenes political work, the hiring of staff, the fundraising, that will continue."

"It's early in the process," said Jennifer Palmieri, Edwards's press secretary. "There is plenty of time for campaigning later."

Sen. John Edwards (D-N.C.) will visit Fort Bragg, not New Hampshire.Rep. Richard A. Gephardt (D-Mo.) said Iraq is part of war on terrorism.