Howard Dean (search) is airing a new anti-war ad in Iowa while plotting to stem Wesley Clark's (search) surge in New Hampshire, where the race has closed to within 10 percentage points and forced Dean to shift strategy.

Locked in a close four-way fight in Iowa, site of the kickoff caucuses Jan. 19, Dean spent the day in Vermont with an eye toward New Hampshire's Jan. 27 primary. Private polling by two campaigns in New Hampshire showed that Dean's lead has shrunk to single digits from a first-of-the-year high of about 25 percentage points, officials said on condition of anonymity.

"Where did the Washington Democrats stand on the war?" an announcer says in Dean's ad, which drew protests from his rivals. "Dick Gephardt (search) wrote the resolution to authorize war. John Kerry and John Edwards both voted for the war."

Clark was spared criticism in the ad, but officials familiar with Dean's strategy said the retired Army general is about to become a campaign target.

Concerned that Clark is closing the gap while the political world focuses on Iowa, Dean campaign aides in New Hampshire plan to deploy surrogates and other campaign tactics to question Clark's shifting views on the war, ties to the Republican Party, commitment to abortion rights and special interest connections.

There are no plans to run ads criticizing Clark before Iowa's caucuses. Dean campaigns in New Hampshire on Wednesday. Aides expect he will be asked about Clark's rise, and they said he may use the opportunity to point out differences between his record and Clark's.

The anti-war ad and sharpened rhetoric are part of a risky strategy for Dean because Iowans traditionally reject negative campaigning in the run-up to the caucuses.

Dean campaign manager Joe Trippi said aides are attentive to Clark's rise, but not surprised by it. The retired Army general bypassed Iowa, allowing him to corner the market on New Hampshire politics.

"He's been shooting free throws by himself on one end of the court while we've been throwing elbows at each other at the other end," Trippi said, casting the Iowa-New Hampshire split in basketball terms.

Mo Elleithee, a spokesman for Clark in New Hampshire, said the Dean campaign was getting nervous. "Clearly, they're hearing our footsteps, and they're resorting to the tired, old politics of attacks."

With polls showing Dean running strong in key early states, he's come under increasing fire from his rivals.

The attention has forced him to balance the need to respond to attacks against the fallout from doing so. Trippi said last week that Dean would try to remain above the fray while aides counter critics, because the candidate had been thrown off message while responding to attacks.

But Dean waded back into the fight Monday, when he criticized his rivals by name and said he was tired of being treated like a "pincushion."

The shift was a welcome return to form, said some backers.

Courtney Work, an organizer for Dean's campaign, said Dean been "up and down," but the aggressive tactic is his strength

"I like what he did yesterday," she said. "I think it's important for him to be himself, reminding people of why he jumped into the race."

At least one rival warned that Dean's more aggressive stance could backfire with voters weary of assaults.

"What people are hungering for here in Iowa is a positive, uplifting campaign of hope, which is what my campaign is about," said Edwards.

The decision to shift gears came at a high-level meeting on Monday in which Dean was urged by top advisers to revert to his earlier message that had moved him from an obscure former governor of Vermont to a front-runner.

They warned Dean this was no time to be cautious, and the new pitch was described as: "This campaign is about the people against the establishment and you are the people."

Dean also has developed an aggressive damage-control strategy designed to confront potential problems before they blow out of proportion.

An example of that came last week when Dean claimed a prized endorsement from four-term Iowa Sen. Tom Harkin. Participants in that decision said Harkin notified Dean by phone Thursday night that he had decided to endorse. Within hours, a story broke of a videotape in which Dean said the caucuses are dominated by special interests.

Knowing the sensitivity of the issue in Iowa, where the leadoff caucuses are a prized event, Dean quickly called Harkin again, giving him a chance to change his mind if the flap proved embarrassing.

After examining a transcript of the exchange, Harkin decided to move forward, and the endorsement was announced Friday.