Barack Obama routed Hillary Rodham Clinton in a racially-charged South Carolina primary, regaining much-needed campaign momentum with the help of black voters in the prelude to next month's coast-to-coast presidential nomination competition in which nearly half the US states will vote.Former Sen. John Edwards, who has yet to win any of the early state contests, was running third, a sharp setback in his native state where he triumphed in his 2004 vice presidential campaign.Landslide margins among black voters fueled Obama to his win, allowing him to overcome the edge that Clinton and Edwards had among whites in the first Southern state where the Democrats competed.South Carolina's Democratic race was particularly significant for Obama, who is aiming to become the US's first black president, because it was the first contest in which blacks were expected to factor large in the outcome. Blacks accounted for about half of the voters, according to polling place interviews, and four out of five supported Obama. Black women turned out in particularly large numbers. Obama, the first-term Illinois senator, got a quarter of the white vote while Clinton and Edwards split the rest."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."The audience had chanted "Race doesn't matter" while they awaited Obama's appearance.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 health care, I will focus on the solutions needed to move this country forward," she said.Returns from 86 percent of the state's precincts showed Obama winning 54 percent in the three-way race, Clinton gaining 27 percent and Edwards at 19 percent.Obama also gained at least 11 convention delegates and Clinton won at least six. Another 28 remained to be allocated on the basis of the results.The South Carolina victor also gained an endorsement from Caroline Kennedy, who likened Obama to her late father, President John F. Kennedy."I have never had a president who inspired me the way people tell me that my father inspired them," she wrote on The New York Times opinion page. "But for the first time, I believe I have found a man who could be that president - and not just for me, but for a new generation of Americans."The victory was Obama's first since he won the kick-off Iowa caucuses on January 3. Clinton, a New York senator and former first lady, scored an upset in the New Hampshire primary a few days later. They split the Nevada caucuses, she winning the turnout race, he gaining a one-delegate margin. In a historic race, she hopes to become the first woman to occupy the White House, and Obama is the strongest black contender in history.The vote Saturday also marked the end of the first phase of the campaign for the presidential nomination, a series of single-state contests that winnowed the field and conferred co-front-runner status on Clinton and Obama, but had relatively few delegates at stake. That all changes on February 5, when 22 of the 50 states hold contests in a virtual nationwide primary.The runup to South Carolina was marked by a week of mud-slinging on the part of Clinton and Obama, with the two candidates exchanging pointed jabs and accusations as Clinton's husband, former President Bill Clinton weighed in on his wife's behalf. That prompted Obama to complain that he felt he was running against two Clintons.The loss was not entirely unexpected for Clinton. Her husband down-played the likelihood of her carrying a state where Obama would carry the support of blacks. With her husband campaigning on her behalf, Clinton focused her sights on other major races - a strategy she continued Saturday by flying to Tennessee while Obama and Edwards arranged to speak in South Carolina to supporters after the polls closed.The February 5 races offer more than 1,600 convention delegates while a total of 2,025 delegates are needed to secure the Democratic nomination. South Carolina offers 45.For the Republicans, the last major contest before the so-called "Mega Tuesday" primaries and caucuses is Tuesday's primary in Florida, where Mitt Romney and John McCain were leading in polls.In South Carolina, half the Democratic voters said the economy was the most important issue in the race. About one quarter picked health care. And only one in five said it was the war in Iraq, underscoring the extent to which the once-dominant conflict has faded in the face of recession fears.Roughly half the voters said Bill Clinton's campaigning for his wife was very important to their choice.The exit poll was conducted by Edison Media Research and Mitofsky International for The Associated Press and the networks.After playing a muted role in the earlier contests, the issue of race dominated an incendiary week that included a shift in strategy for Obama, a remarkably bitter debate and fresh scrutiny of the former president's role in his wife's campaign.Clinton and Obama swapped accusatory radio commercials earlier in the week.The former first lady aired an ad saying Obama had once approved of Republican ideas. His camp responded quickly: "Hillary Clinton will say anything to get elected." First she, then he, pulled the commercials after a couple of days.Each side accused the other of playing the "race card," sparking a controversy that frequently involved the former president."They are getting votes, to be sure, because of their race or gender. That's why people tell me Hillary doesn't have a chance of winning here," Bill Clinton said at one stop, strongly suggesting that blacks would not support a white alternative to Obama.Clinton campaign strategists denied any intentional effort to stir the racial debate. But they said they believe the fallout has had the effect of branding Obama as "the black candidate."By week's end, one poll indicated that Obama's support among whites in the state had dropped sharply.Given the bickering, Edwards looked for an opening to reinvigorate a candidacy all but eclipsed by the historic campaign between Obama and Clinton. He went on the "Late Show with David Letterman" at midweek to say he wanted to represent the "grown-up wing of the Democratic party."Meanwhile, in the Republican race in Florida, McCain accused Romney of wanting to set a timetable to withdraw US troops from Iraq, drawing immediate protest from his rival who said: "That's simply wrong and it's dishonest, and he should apologize."The heated exchange underscored the growing intensity of the Republican race ahead of the state's pivotal primary. A fairly civil debate over economic records and leadership credentials spiraled into an all-out showdown as the two campaigned along the state's southwest coast.Polls show McCain and Romney locked in a tight fight for the lead in a state that offers the winner a hefty 57 delegates to the Republicans' nominating convention next summer and a shot of energy heading into the February 5 races.McCain received a key endorsement Saturday from Florida's Republican governor, Charlie Crist.In Orlando, Rudy Giuliani, the former New York mayor trailing in polls and trying to climb his way back into the leaders pack, sought to take the high road, saying he wanted to "remain positive".There will be more than 1,000 Republican delegates at stake on February 5, enough to give a candidate a substantial boost toward the 1,191 needed to win the presidential nomination.