OLUMBIA, S.C. - Escalating the verbal skirmish they have carried on for weeks, Governor George W. Bush and Senator John McCain used their final debate before the South Carolina primary to point out flaws in each other's campaigns, brushing quickly past questions about budget surpluses and tax cuts to quarrel about the race itself.
Their well-known differences over the surplus - McCain would use much of it to pay down the national debt while Bush favors a major tax cut - took up some of the debate. But just four days before the next primary, which could determine the outcome of the Republican race, the most contentious moments arose over the campaign's attacks and counter attacks.
Prodded by the moderator, Larry King, the two leading candidates and Alan Keyes also fielded questions about moral issues and leadership. And they often took advantage of the more freewheeling CNN format to interrupt each other.
Bush and McCain quarreled over each other's campaign commercials and leadership qualities. Bush was questioned about his decision to speak at Bob Jones University and his refusal to meet with a gay Republican group.
But the emotional epicenter of the encounter came when Bush traced the negative trend in the campaign to McCain's comparison of him, in a campaign ad, to President Clinton. ''That's about as low a blow as you can get in the Republican primary,'' Bush said.
Recalling the handshake agreement the two men had to avoid negative ads, Bush, looking disappointed and speaking in a soft voice, said he could simply could not allow his opponent to define him in that way.
McCain, too, responded softly, and with scorn, saying Bush should be ''ashamed'' for appearing at a campaign stop with a ''fringe veteran'' who insulted McCain.
''I don't know if you can understand this, George, but that really hurt. That really hurt,'' McCain said.
''Yeah,'' Bush said quietly.
''You should be ashamed of sponsoring an event with that man,'' McCain continued.
''The man was not speaking for me... if you want to know my opinion about you, John, you served our country strongly and admirably,'' Bush said.
McCain largely absolved himself of blame for the tone of the campaign, saying he had taken down all but his most positive campaign advertising.
That prompted Bush, seated scarcely three feet away, to wave a printed flyer that he said attacked him harshly and had turned up on a car windshield earlier in the day.
''That is not by my campaign,'' said McCain.
''It says paid for by McCain committee,'' was Bush's instant rejoinder.
The back-and-forth on the issue only ended when Keyes, the only other Republican candidate remaining, had his say, taking note of the many nations viewing the international CNN broadcast.
''Is this pointless squabbling really what we want them to see? We are talking about electing the president of the United States,'' Keyes said. ''All I'm sitting here listening to is these two guys going on about their ads?''
With the South Carolina primary only four days away, both Bush and McCain were struggling to surge ahead in polls that have showed them in a dead heat. For Bush, a win in South Carolina would provide a much-needed boost in confidence, following his surprise loss in New Hampshire. For McCain, it would continue the momentum of his overwhelming win.
But last night, at least, each candidate seemed more focused on the other than on the larger race at hand.
During an early phase of the debate which dealt with foreign policy, McCain said he would be willing to meet, as a candidate, with the new Russian leader, Vladimir Putin, and suggested that the United States should consider taking action in ''terrible situations'' such as Rwanda, where genocide took place.
McCain also said he would be willing to ''arm and train forces'' outside the United States that were committed to overthrowing governments in places such as Libya and Iraq. He called it his ''rogue nation rollback'' policy.
Asked if he would meet with Putin, Bush said: ''Probably not. Maybe.'' As for overseas intervention, he discouraged the idea of American soldiers serving as ''peacekeepers around the world.'' The US military, he said, was already ''overdeployed and undertrained.''
The Texas governor placed the most stress on what he called his leadership traits. He cited his endorsement by many governors and members of Congress, saying he was picked by them ''because they know me well, they know my capacity to bring people together.''
McCain acknowledged that he was not popular among many of his congressional colleagues ''because I've taken on the Iron Triangle, the special interest money.... I did not make a lot of friends.'' He said his campaign was recruiting independents and reconstituting the old Reagan Democrats bloc in order to revive a Republican Party that ''has lost its way.''
Keyes questioned Bush's failure to question the policies of Bob Jones University when he appeared there earlier this month. The South Carolina school is a center of white Protestant fundamentalism and opposes interracial dating. He also complained that McCain rode a ''high horse'' of ''truth and integrity'' but also failed to challenge the institution's ''racial and religious bigotry.''
Bush said he did not support the school's policies and used his chance to speak there to talk about ''the principles of compassionate conservatism.''
McCain said he had not been asked to speak at the school. ''If I had been invited, I would have said: Look, what you're doing or standing for is idiotic and incredibly cruel.''
When Bush was asked about his refusal to meet with Log Cabin Republicans, a gay group, he seemed slightly flustered. ''I've got gay supporters,'' he said. He pointed out that the organization had been raising money for McCain.
''I'll meet with them, not necessarily agree with them,'' McCain said. He opposed same-sex marriages, he said, but approved of the military's ''don't ask, don't tell'' policy, which had been embraced by former General Colin Powell, a prominent Republican.
After Bush added that he, too, supported the military's quiet acceptance of homosexuals in the ranks, Keyes dissented. The talk show host, who often criticizes homosexuality, called it a ''dishonest, shameful policy'' and said it was ''a little disingenuous'' to suggest that Powell and other generals approved of the arrangement. He said it had been imposed on the military by the Clinton administration.
''To imply that Colin Powell was coerced is a great disservice,'' said McCain. He said the former head of the joint chiefs of staff could ''serve anywhere he wants in my administration,'' including vice president.
Bush said it was premature to discuss potential appointments. ''It cheapens the process,'' he said.
Both Bush and McCain spurned hypothetical questions about abortion regarding their own daughters, and when Keyes persisted, McCain told him bluntly: ''I hope you'll respect my position and not bring my daughter'' into a national controversy.
King, the moderator, asked Bush, a governor who has presided over numerous executions, about a recent decision by Illinois Governor George Ryan to suspend the death penalty. Bush said he considered each case carefully. ''There's no doubt in my mind that each person who's been executed in our state was guilty of the crime committed. I support the death penalty for this reason: When the death penalty is administered in a swift and sure and fair way, it will save lives.''
McCain tried to capitalize on the relative inexperience of the Texas governor, who was first elected to public office in 1994, as he emphasized his commitment to paying down the national debt. McCain cast Bush's proposal to spend the budget surplus on tax cuts as youthful and irresponsible. ''It's not the Washington mentality, it's the grown-up mentality,'' McCain said. ''We've got obligtions, and we've got to pay them off.''
Bush, sounding slightly irked by the response, reverted to a line he has repeated throughout the campaign. With a tax cut, he said, the economy would no longer be in danger of crashing as it is now. Additionally, he said, the Social Security surplus would be used to pay down the national debt.
''Grown up or not grown up - I know that's kind of a line you're trying to come across with,'' Bush said. ''But either you trust people or you trust the government.''
Larry King, host of CNN's Larry King Live, asks a question to Republican presidential candidates Sen. John McCain of Arizona, left, Alan Keyes, center, and Gov. George W. Bush of Texas, during Tuesday's presidential debate. (AP Photo)