COLUMBIA, S.C. — Barack Obama surged to a convincing victory in the South Carolina primary yesterday, a verdict that leaves the Democratic nomination far from settled and possibly still a three-way race heading into the pivotal 22-state contest on Feb. 5.

Obama's roughly 2-1 victory over Hillary Rodham Clinton was the most convincing of any contest so far, and came after a bitter fight with the New York senator in a contest singed by race, allegations of distortions and arguments over which Democrat is the most likely to win the White House in November.

"After four great contests in every corner of this country, we have the most votes, the most delegates and the most diverse coalition of Americans that we have seen in a long, long time," Obama told supporters in Columbia.

Exit polls showed his win was forged through significant majorities of black and young voters and about a fourth of white voters. In victory, Obama sought to transcend the racial edges that had marked the campaign here.

"I did not travel around this state over the last year and see a black South Carolina or a white South Carolina," Obama said. "I saw South Carolina."

Returns showed Obama with 55 percent of the vote and Clinton 27 percent. John Edwards had 18 percent and won only in his home county of Oconee.

Edwards gave no indication he was finished overall. He won South Carolina in 2004, but expectations for him were so low this time around that he may have discovered a niche to remain in contention: that he is the most seasoned, even-handed and electable candidate between two bitter rivals ahead of the field.

Meanwhile, Obama, who won the Iowa caucuses a little more than three weeks ago, seized back the winner's spotlight that Clinton had taken from him by winning contests in Nevada and New Hampshire.

"The choice in this election is not about regions or religions or genders," Obama said at a boisterous victory rally. "It's not about rich versus poor, young versus old and it's not about black versus white. It's about the past versus the future."

Clinton issued a statement saying she had called Obama to congratulate him on his victory. She quickly turned her focus to the primaries ahead. "For those who have lost their job or their home or their healthcare, I will focus on the solutions needed to move this country forward," she said.

OBAMA MOMENTUM

Caroline Kennedy, daughter of late President John F. Kennedy, has endorsed Obama, citing in part his "special ability to get us to believe in ourselves."

"I have never had a president who inspired me the way people tell me that my father inspired them," she wrote in the New York Times. "But for the first time, I believe I have found the man who could be that president — not just for me, but for a new generation of Americans."

Audrey Haynes, a political scientist at the University of Georgia, said the win will give Obama needed momentum going into Feb. 5, which includes the big prizes of California, New York and Illinois, as well as significant second-tier states such as Georgia.

Clinton has maintained significant but not dominant poll leads in many Feb. 5 states, but that was before the attention turned to them. The campaign calculus now shifts from the retail politics of January to a national test of tactics, resources and resiliency.

There are three questions going forward: Did Obama's victory expose a race-based split in the party? Will the tactical and rhetorical nastiness between Clinton and Obama continue as the stakes rise? And will Bill Clinton continue to be a controversial, headline-grabbing figure?

Obama won in South Carolina by getting a significant percentage of black voters and pulling in at least one in four white voters.

One typical Obama voter was Wesley Abingon, 30, of Westminster, who said he could not find many issues differences between Clinton and Obama. So he went with Obama's claims of being a new and unifying voice.

"I really decided when I went into the voting machine what made the difference was his whole approach and the way he speaks," Abingon said.

The South Carolina Democratic primary was the first in 2008 with a significant number of black voters. Race and faith became strong undertones in the contest between Obama and Clinton. Each side accused the other of playing the race card, and the debate got so rough between them that Edwards declared himself representative of the "grown-up wing of the Democratic Party."

Edwards may use that moniker to push on, believing he could end up the prime challenger to whoever survives an Obama-Clinton smackdown Feb. 5.

In the months before South Carolina, Clinton surrogates publicly suggested Obama sold drugs (in an autobiography, he admitted to using cocaine); referred to his middle name — "Hussein" — and falsely implied that he was a product of a Muslim religious school; and even suggested that former President Bill Clinton was more authentically black than Obama, the son of a black man and white woman.

Bill Clinton stumped widely for his wife in South Carolina. He suggested that because people were voting on the basis of race or gender, his wife would not win because of South Carolina's heavy black population.

A PARTY DIVIDED?

Looking ahead, "Clinton is clearly the front-runner in key states" that vote Feb. 5, said Todd Shaw, a University of South Carolina political scientist. "But we are seeing sort of her trending a bit downwards, and him upwards. We'll see."

Shaw said the debate in South Carolina probably "helped to mobilize at least some undecided African-American voters to Obama," and that, as a result, "there is a lingering question about party unity come November."

Even before the votes in South Carolina were counted, gamesmanship over the Florida primary on Tuesday had begun. Democrats there are angry that Edwards, Clinton and Obama have ignored the state while adhering to a Democratic National Committee penalty on states that moved up their primaries without DNC permission. The DNC has stripped the state of its delegation to the national convention in August.

Clinton leads in polls in Florida, and her acolytes tried to pump up the state's significance, delegates or no delegates. Clinton on Friday said Florida should get its convention representation back. Obama aides accused her of last-minute pandering.

Gannett News Service, Associated Press and Bloomberg News Service contributed to this report.