WASHINGTON — As the Republican presidential race devolves into a five-man free-for-all of sustained attacks and sharp rejoinders, one pair of candidates, Mayor Giuliani and Michael Huckabee, has avoided direct conflict, exchanging more compliments than criticism.

Mr. Huckabee, who has leapt to second in the Iowa polls, has drawn increasing fire from GOP contenders Mitt Romney and Fred Thompson, but not from Mr. Giuliani, who has described him as “wonderful.”

The former Arkansas governor seemed to respond in kind yesterday when he took Mr. Giuliani’s side in the former New York mayor’s bitter fight with Mr. Romney over their respective records as a mayor and governor.

“I think Mitt was the one who went after Rudy more than Rudy went after Mitt,” Mr. Huckabee told reporters in a conference call, when asked for his thoughts on the dispute that has played out in New Hampshire in recent days. Messrs. Romney and Giuliani have taken harsh shots at each other on a range of issues, including spending, taxes, immigration, and executive appointments.

The former Massachusetts governor, Mr. Huckabee suggested, didn’t know what he was getting into with Mr. Giuliani. “Mitt’s going to learn the hard way that if you go after Rudy, you better be prepared to take one upside the head, because Rudy’s an experienced fighter and knows how to do it. Mitt may have jumped into the cage with a guy that knows not only how to take a punch but to deliver one back.”

The comments only add to the perception that even as he rises in the polls, Mr. Huckabee is angling for the vice presidential slot on the Republican ballot, should Mr. Giuliani win the nomination. As an affable Southerner with a solidly conservative record on social issues, Mr. Huckabee could provide precisely the kind of geographic and political balance needed for a ticket topped by an occasionally abrasive New Yorker who supports abortion rights, analysts say.

A Republican pollster, Whit Ayres, said Mr. Huckabee was an “obvious” potential running mate for Mr. Giuliani. “The mayor is going to need a social conservative on the ticket or someone that appeals to social conservatives to unite the party,” he said.

The Giuliani campaign declined to comment on Mr. Huckabee’s remarks, but the former mayor has praised him recently. “Huckabee’s a wonderful man,” he said on Fox News in October, although he demurred when pressed about whether he would choose him for the vice presidential pick. He repeated the sentiment earlier this month, the network reported. “I have great regard for Mike Huckabee, and I have nothing bad to say about him,” Mr. Giuliani said while campaigning in Iowa.

Vice presidential speculation aside, the pleasantries could be a smart strategy for Mr. Giuliani, political analysts say, because he stands to benefit from Mr. Huckabee’s surge in Iowa, where Mr. Romney is banking on the momentum that a convincing win would give him heading into the New Hampshire primary five days later.

“Huckabee’s success in Iowa could give Romney a hollow victory and cause things to be wobbly in the Granite State,” a GOP strategist who ran Bob Dole’s campaign in 1996, Scott Reed, said.

Mr. Reed said it was too early to say if Mr. Huckabee’s defense of Mr. Giuliani was calculated with the vice presidency in mind. The two candidates, he said, had little reason to denigrate one another because for now, they are targeting different constituencies in the Republican Party and even voters in different states. Mr. Huckabee has focused almost exclusively on Iowa, while Mr. Giuliani has emphasized larger states, and more recently, New Hampshire.

Aides to Messrs. Giuliani and Huckabee denied any kind of nonaggression pact, noting that both candidates typically criticized party rivals only in response to opponents who attacked first. “There hasn’t been a concerted effort,” a spokeswoman for Mr. Huckabee, Alice Stewart, said.

Strategists pointed out that the kind words between the two hopefuls could disappear quickly, particularly as they prepare for a CNN/YouTube debate in Florida tomorrow night.

Mr. Giuliani and Senator McCain, for example, had praised each other for months, even spurring talk that the Arizona senator could endorse Mr. Giuliani if his fund-raising struggles and staff exodus over the summer forced him out of the race. Now, a resurgent Mr. McCain is going after him aggressively, saying yesterday that Mr. Giuliani “has no national security experience that I know of.”

Mr. Huckabee also has sharpened his rhetoric on his opponents. After defending Mr. Giuliani against attacks by Mr. Romney, he took an unprompted shot at Fred Thompson, whose campaign on Sunday sent out a flurry of press releases criticizing Mr. Huckabee on fiscal policy, abortion, and immigration. “It was just absolutely amazing, the barrage,” Mr. Huckabee said, before referencing the criticism of Mr. Thompson as a disengaged campaigner. “I think it was the most activity we’ve seen out of Fred since he announced his run for the presidency. He was pretty energetic yesterday, cranking out those hit pieces.”