By RICHARD L. BERKE

HARLESTON, S.C., Feb. 19 -- Gov. George W. Bush surged to victory in the South Carolina primary today, reclaiming his spot as the unmistakable front-runner for the Republican presidential nomination. But Senator John McCain vowed to persevere, warning that if Mr. Bush was nominated, the Republicans would lose in November.

Riding a record primary turnout, Mr. Bush rallied Republicans across the state, overwhelming Mr. McCain's drive to attract independents and Democrats like those who helped the senator in his stunning victory in New Hampshire on Feb. 1.

But in a surprisingly combative concession speech here tonight, Mr. McCain showed no sign of yielding as the race quickly turns to contests in Michigan and Arizona on Tuesday. In a clear stab at Mr. Bush and what he called a "negative message of fear," Mr. McCain declared that he would offer "a choice between a record of reform and an empty slogan of reform, a choice between experience and pretense."

In his victory speech in Columbia about an hour later, Mr. Bush looked right the man who had threatened to unhinge his campaign in New Hampshire nearly three weeks ago and set his sights on Vice President Gore.

"South Carolina has spoken -- and tonight there are only 263 days more to the end of Clinton-Gore," he declared. "My reform agenda stands in stark contrast to the current administration."

His only mention of Mr. McCain came near the close of his speech, when he thanked him for a tough fight and lumped him with Alan Keyes, the former State Department official who also ran.

"I want to commend two tough competitors, Senator John McCain and Ambassador Alan Keyes," he said. "I want to thank their supporters for their hard work in fighting for a cause in which they believe."

With 99 percent of election districts reporting, the vote was: Bush 301,050 (53%); McCain 237,888 (42%); Keyes 25,510 (5%).

Mr. Bush's support was wide and deep; he captured the majority of nearly every demographic group. Most significant, the reformer mantle that he appropriated from Mr. McCain after the senator's stunning triumph in New Hampshire seems to have paid off. Voters told pollsters today that they liked Mr. Bush's reform message and they suggested that Mr. McCain was too much of an outsider.

Mr. McCain had staked his prospects on the expectation that independents and Democrats would flood to the polls and support him overwhelmingly. Officials estimated that that the turnout was indeed huge, more than double the 276,000 who voted in the primary here four years ago. And independents and Democrats did turn out in larger numbers than in 1996, and they largely backed Mr. McCain.

Still, their numbers were not significant enough to carry Mr. McCain even close to Mr. Bush, who locked up loyal Republicans.

The results were particularly welcomed by Mr. Bush because before New Hampshire he was as many as 20 percentage points ahead of Mr. McCain in polls here; for weeks, the race was neck and neck, with the senator even outpacing Mr. Bush in some surveys.

In his speech tonight, Mr. McCain looked upbeat, but spoke the words of a politician unwilling to yield. He even suggested that Mr. Bush's advertising barrage was out of bounds. "I am going to keep fighting clean," he said. "I am going to keep fighting fair." Mr. McCain's advisers were even more blunt. They asserted that Mr. Bush's hard-line conservative message in South Carolina would put off voters in the upcoming contests.

"Ralph Reed, Pat Robertson and Jerry Falwell are to be congratulated," said John Weaver, Mr. McCain's political director.

By winning comfortably here, Mr. Bush is better positioned in Michigan and Arizona, the senator's home state. Mr. McCain now faces enormous pressure to show that his victory in New Hampshire was not an anomaly.

But the voting here was particularly distressing for Mr. McCain because South Carolina was one of the few remaining states where independents and Democrats could vote in the primary. Now, most of the voting is in states where only Republicans can participate; and in many of them Mr. Bush has the backing of the governors.

Though he limped out of New Hampshire, Mr. Bush engineered a comeback here by displaying a scrappy determination to work for the nomination that was never apparent in the earlier contests. Throughout last year, Mr. Bush swamped his rivals in the polls -- effortlessly it seemed -- and forced most of them to quit the race.

Had Mr. McCain won in South Carolina, he may have experienced an important lift that could have led some Bush backers to begin to defect.

Yet Mr. Bush's strong showing came at a price: He overwhelmed Mr. McCain by pouring more than $3 million in an advertising blitz into this state, and in doing so continued to deplete what had been a flush treasury. Mr. McCain's threat also forced Mr. Bush to abandon his long-promised posture of never stooping to commercials attacking his rival.

And in appealing to conservatives on issues ranging from abortion to whether the Confederate battle flag should fly over the State Capitol, Mr. Bush took a sharp turn to the right. He abandoned his strategy of hewing to the middle, a move that Mr. McCain's advisers were quick to note tonight could haunt the governor in a general election.

But it seemed clear that the barrage of commercials worked to Mr. Bush's advantage.

Of the voters interviewed today by Voter News Service, a consortium of television networks and The Associated Press, about a third said they waited until the last week or so to decide whom to vote for, and most of them backed Mr. Bush.

Voters were more likely to say that Mr. McCain had unfairly attacked Mr. Bush than they were to say that Mr. Bush was the one attacking Mr. McCain.

In a heartening finding for Mr. Bush as the voting moves to a more varied electorate, he had the support of nearly every demographic group, including men, women, rich and poor, young and old. Even veterans -- whom Mr. McCain had reached out to in an all-out turnout drive -- split their vote between Mr. McCain and Mr. Bush.

More than a third of voters said they considered themselves part of the religious right, and more than two-thirds of those voters backed Mr. Bush. If religious conservatives were removed from the mix, Mr. McCain would have won, barely.

The exit polls also found that Mr. Bush's drumbeat of reform and leadership, as well his emphasis on moral values, meant a lot when voters decided who to support.

Although Mr. Bush and Mr. McCain were viewed as reformers, Mr. Bush was seen as more of one. Voters were not convinced that Mr. McCain had been true to his word on the issue of campaign finance, a subject Mr. Bush hammered Mr. McCain on in his advertising.

Nearly half the voters said Mr. McCain says one thing but does another on campaign finance -- and they voted overwhelmingly for Mr. Bush.

Asked what issue played the greatest role in their decision, voters said moral values, and they mostly backed Mr. Bush. Among those who cited Social Security and Medicare, Mr. McCain was more popular.

But the issue of tax cuts was low on the list of voters' priorities, even though Mr. Bush made it a centerpiece of his campaign.

Although Mr. Bush succeeded in being portrayed as a reformer, Mr. McCain was viewed as a man who stood up for his beliefs. That is the character trait that voters said they cared most about, and more than half of those voters backed Mr. McCain.

Even so, voters said they considered Mr. Bush more of a leader -- and a more potent rival against the Democrats in November.

Karl Rove, Mr. Bush's chief strategist, attributed the results today to a return to the roots of the 1994 governor's campaign, when Mr. Bush talked about reforms he favored -- and spoke in specific terms. He also said voters were impressed with a tougher, more assertive Mr. Bush.

"Both of these guys are going to come out of here with roughly equivalent positives and negatives, and yet Bush is going to come out of here with a substantial win," Mr. Rove said. "And I think it's because people looked at him and saw how he handled adversity, saw how he passed through this test, and liked what they saw." He added, "People wanted to see, if you care about something, are you somebody who is going to fight for it?" Ninety-eight percent of voters in the primary were white, more than half were men and more than 4 in 10 were over the age of 60. Nearly half said they had college degrees; 3 in 10 served in the military. Blacks were virtually nonexistent in the voting, even though in general elections in 1996 and 1998 they made up a quarter of the vote.

The voters here are more conservative than most; nearly a quarter described themselves as very conservative, and another 4 in 10 called themselves somewhat conservative.

Several of Mr. Bush's aides said his father, former President George Bush, was so nervous about the voting that he called them several times to find out the latest intelligence.

Mr. Rove said he alerted Governor Bush about the encouraging exit polls this afternoon and then called his father.

The former president, Mr. Rove said, uttered the word "relieved."