Hillary Clinton appeared to be heading for a big victory in West Virginia over front-runner Barack Obama in the Democratic presidential race tonight, but it could be too late for her White House bid.
Ms Clinton has an advantage of at least 20 points in most opinion polls in West Virginia, a bastion of the white working-class voters who have become her strongest supporters in the battle for the Democratic nomination.
But Mr Obama retains a nearly insurmountable advantage in delegates who will select the nominee at the party convention in August. A big win in West Virginia for the cash-strapped Ms Clinton will make barely a dent in Obama's advantage.
Both candidates returned to their jobs in the US Senate this morning, where they exchanged a few words while voting for a measure aimed at lowering oil prices. Record-high gas prices have been a key issue in the campaign.
A Clinton victory in West Virginia could raise doubts about Mr Obama's ability to win important swing states in the November election against Republican John McCain, one of her top aides said.
"I think Democrats across the country tomorrow will be asking themselves why Senator Obama, with all of his money, with all of the great press, with voters being told that he is the inevitable nominee, why did Senator Obama lose West Virginia by 15 points or so?" Clinton spokesman Howard Wolfson said.
West Virginia has just 28 delegates at stake in today's voting, which ends at 7.30pm (11.30pm Irish time). Results are expected shortly afterward.
Ms Clinton, a New York senator and former first lady, has vowed to keep fighting despite her dwindling prospects and a mounting campaign debt.
"I wouldn't be doing this if I didn't believe that I could be the best president for West Virginia and America and that I was the stronger candidate to take on John McCain in the fall," she said at a rally in Logan, West Virginia yesterday.
Mr Obama, already looking to November, made a quick appearance in West Virginia yesterday and announced plans to visit general election battlegrounds Missouri, Michigan and Florida.