Washington: Hillary Clinton won a landslide victory over front-runner Barack Obama in West Virginia and vowed to keep her beleaguered White House bid alive until voting ends in the Democratic race.

Clinton hoped her crushing defeat of Obama on Tuesday, 67 per cent to 26 per cent, would slow his march to the Democratic nomination and bolster her case that she is the Democrat with the best chance to beat Republican John McCain in November's election.

Obama, who would be the first black US president, retains a nearly unassailable advantage in delegates who will select the nominee at the party convention in August. West Virginia had only 28 delegates at stake.

"This race isn't over yet. Neither of us has the total delegates it takes to win," the New York senator and former first lady told a victory celebration in Charleston, West Virginia.

"I am more determined than ever to carry on this campaign until everyone has had a chance to make their voices heard," she said, looking ahead to the final five nominating contests that conclude on June 3.

Obama made only one brief campaign stop in West Virginia before the contest and stayed far away, when he visited the general election battleground of Missouri and looked ahead to a November match-up with McCain.

"A vote for John McCain is a vote for George Bush's third term," Obama said in Cape Girardeau, Missouri. "We cannot afford any more of the Bush-McCain programme."

Obama did not appear in public after the voting ended in West Virginia, but a campaign spokeswoman said he left Clinton a congratulatory message on her mobile phone. He is scheduled to make stops in the general election battleground states of Michigan on Wednesday and in Florida next week.

A delegate count by MSNBC gives Obama 1,881 delegates to Clinton's 1,721. That leaves him 144 short of the 2,025 needed to clinch the nomination.

Democrats win

Mississippi Democrat Travis Childers won a US House of Representatives seat in a special election on Tuesday that analysts said should serve as a warning to Republicans gearing up for November's congressional elections.

Childers defeated Greg Davis in a run-off to fill a vacant seat in Mississippi's first congressional district, according to projections reported by local media.

Vice-President Dick Cheney and the state's Republican governor campaigned against Childers in a district considered safe territory in part because it voted heavily for US President George W. Bush in 2004. The win expanded the Democratic majority in Congress to 236 versus 199 seats held by the Republican Party.