The Republican candidates for president are beginning to confront each other directly, as a few of the hopefuls last night took shots at Mayor Giuliani, Governor Romney, and others in a Republican debate in South Carolina.

Looking to advance in a crowded field, long-shot candidates such as a former Virginia governor, James Gilmore, and a former Arkansas governor, Michael Huckabee, chided Mr. Giuliani for his support of abortion rights.

The candidates were far more comfortable assailing Democrats, and Mr. Huckabee struck gold early on with a dig at a former North Carolina senator, John Edwards: “We’ve had a Congress that’s spending money like John Edwards at a beauty shop,” he quipped, drawing laughter and applause for his reference to Mr. Edwards’s infamous $400 haircut.

The hits on each other began in polite fashion, as the candidates were clearly uneasy at the prospect of starting a negative campaign eight months before the first ballots are cast.

“I think some of the people on this stage were very liberal in characterizing themselves as conservatives, particularly on the issues of abortion and taxes and health care,” Mr. Gilmore said, referring to the first Republican debate earlier this month in Southern California.

He tiptoed into his criticism, saying the forum, with 10 candidates bunched together on a stage, made it difficult to “single people out.” When pressed, Mr. Gilmore acknowledged that he was referring to Mr. Giuliani for his position on abortion, Mr. Romney for his support of expanding government’s role in health care in Massachusetts, and Mr. Huckabee for presiding over tax increases in Arkansas.

A few minutes later, Mr. Huckabee said he had “great respect” for Mr. Giuliani for his honesty on abortion. He said so even as he stood by an earlier statement in which he compared the former mayor’s stance — he personally opposes the practice but supports a woman’s right to choose — to someone saying they oppose slavery but support allowing others to own slaves.

Mr. Giuliani took the jabs in stride and showed that he had prepared a more cogent answer on the abortion question after appearing to stumble in the first debate. He stood by his support for the right to choose, but he emphasized the need to reduce abortions. He cast his position as in line with the Republican principle of smaller government and more individual choice.

The former mayor had a stronger — and angrier — response when an anti-war Texas congressman, Rep. Ron Paul, suggested that the terrorist attacks of September 11, 2001, occurred because of America’s presence overseas. “I don’t think I’ve ever heard that before, and I’ve heard some pretty absurd explanations for September 11,” Mr. Giuliani said. “I’d ask the congressman to withdraw that comment and tell us he didn’t really mean it.”

Mr. Paul didn’t back down. “They attack us because we’re over there,” he said.

Eager for a chance to assert their strength on the issue of terrorism, almost all of the other candidates tried to get a word in, but the Fox News moderators decided to change the subject.

The second Republican debate was held last night on the University of South Carolina campus in Columbia. The forum was broadcast live on Fox News.

South Carolina is the traditional site of the first Southern primary, and no Republican has won the party’s nomination without winning the state in recent decades.

Not on the stage last night were two prominent Republicans who are considering presidential bids but have yet to declare their candidacies: a former Tennessee senator, Fred Thompson, and a former House speaker, Newt Gingrich.

The scrutiny coming into the debate was on Mr. Giuliani, who faced repeated questions about his position on abortion when the candidates met earlier this month at the Ronald Reagan Presidential Library in Simi Valley, Calif. The former New York mayor said then that it would be “okay” if the landmark Roe v. Wade decision were overturned. Since that night, he has sought a more cogent explanation of his position, which is that he personally opposes abortion but supports a woman’s right to choose.

Mr. Romney, who led all the candidates in fund-raising during the first quarter, has moved up in recent polls in New Hampshire and Michigan following his strong performance at the first Republican debate. But he remains far back in South Carolina, and questions linger about whether his acknowledged shifts in position on key social issues have hurt his campaign.

Last night he also faced criticism from Mr. Huckabee on his health care plan as governor of Massachusetts, which makes health insurance mandatory for all citizens. He defended the program, as he has repeatedly on the campaign trail.