SPARTANBURG -- John Kerry is hoping he has won a big prize in South Carolina.

Kerry's campaign announced Wednesday, the day after his New Hampshire primary victory, that Rep. Jim Clyburn, D-S.C., the highest ranking black official in the state, will endorse him today.

Kerry and other Democratic presidential candidates have been angling for Clyburn's support because the black vote will be critical in Tuesday's South Carolina primary. But some analysts doubt the value of his endorsement for Kerry because other candidates, including Sen. John Edwards of North Carolina, have done more groundwork with black voters in the state.

"Kerry's big problem here is that he never spent a lot of time nurturing the black vote," said Francis Marion University political analyst Neil Thigpen. But the race is close, he noted. "If Clyburn's endorsement brings him one in four black votes, Kerry has a chance to win."

Kerry's press secretary, Stephanie Cutter, said Clyburn's endorsement "is a significant sign of support. ... Rep. Clyburn is a leader in the African-American community."

Clyburn and his staff had no comment on the endorsement report from the Kerry camp. Clyburn has said if he made an endorsement, it would be done in his district; he is scheduled to return to South Carolina today.

Kerry's momentum from his victories in Iowa and New Hampshire will be tested in South Carolina, one of seven states with caucuses or primaries Tuesday.

A poll of 600 likely voters by American Research Group just before the New Hampshire primary showed Edwards in the lead with 21 percent, followed by Kerry, a senator from Massachu-setts, at 17, civil rights activist Al Sharpton at 15 and retired Gen. Wesley Clark at 14. Former Vermont Gov. Howard Dean, who had led in South Carolina in December, had slipped to 9 percent, just ahead of Sen. Joe Lieberman of Connecticut at 5.

Edwards, who finished second in Iowa and fourth in New Hamp-shire, has called South Carolina a must-win state.

Black voters might account for more than 40 percent of the turnout next week, and Edwards has been carefully cultivating the black vote for months. His first stop Wednesday was at a rally in Orangeburg, in the heart of Clyburn's district.

Kerry, meanwhile, has hardly been back to the state since he announced his candidacy here in September. Kerry has won the endorsement of white South Carolina establishment figures such as Sen. Fritz Hollings, but needs the entry into the black community that Clyburn would provide.

Clyburn had supported Rep. Dick Gephardt of Missouri. With the connection to Clyburn's organization, Gephardt had been considered a leading contender here.

But when Gephardt withdrew after his defeat in Iowa, Clyburn's endorsement was up for grabs. Some of Clyburn's staff, including top aide Isaac Williams, joined the Edwards campaign, and most political analysts said they thought Clyburn would endorse Edwards or no one.

If Clyburn makes an endorsement today, it will come just hours before the candidates square off in a debate at Furman University in Greenville.

Kevin Gray, a contributor to Black News in Columbia and author of the upcoming book, "The Death of Black Politics," said Clyburn's endorsement power is not as great as it might seem. "That's white folks' wishful thinking. But black folk see him as an establishment figure. People are going to make up their own minds."

Clyburn himself has said his power is limited, as he believes it should be. "We should not put all our eggs in one basket. It would not do our party a lot of good to have all the black people lined up for one candidate and all the white people for another."

Sharpton's presence could be the wild card. After barely registering in Iowa and New Hampshire, the civil rights leader has substantial support in the black community here.

Clyburn said he understands why Sharpton is popular here. "When people are not afraid to take on unpopular causes, when people are not afraid to speak up and challenge powerful interests, they have almost a built-in following in the black community."

Edwards, born in Seneca, has been emphasizing his upbringing as the son of a mill-worker. He has been running a television ad that talks about the "two Ameri-cas," the difference between the haves and the have-nots.

"That resonates with African-Americans," said University of South Carolina political analyst Blease Graham.

"Edwards has been honoring the NAACP boycott of South Carolina's tourism industry by staying in people's homes while he has been here rather than in hotels," Graham said. The civil rights group called for the boycott to protest the flying of the Confederate flag in front of the state capitol.

Although Dean has hired a lot of black operatives to work for him in the state, it has not translated into much support, said Francis Marion's Thigpen.

Dean got into trouble with some black voters when he said he wanted to attract "guys with Confederate flags on their pickup trucks."

David Mack, Dean's state chairman, who is black, said the media misinterpreted that quote. "The basis of that statement is that we need to form a true coalition in this state and have people vote in their best interests, as opposed to race."

-- Gil Klein is a reporter in Media General's Washington Bureau. E-mail him at gklein@mediageneral.com.