Exit polls in West Virginia showed two of every 10 white voters said race was a factor in their decision, and only a third of those said they would support Obama against McCain. Obama gained more than a quarter of the white vote in West Virginia, which has a small black population.
Less than an hour after the polls closed, Clinton, whose campaign is at least $20 million (10.3 million pounds) in debt, sent supporters text messages and e-mails, urging them to donate money to her campaign, according to The New York Times. She said her strength in big states like Ohio and Pennsylvania that are critical in a presidential election made her the best candidate against McCain.
She made a direct appeal to the remaining Democratic voters and superdelegates - party officials who can back any candidate and will help decide the nominee.
"I'm asking people to think hard about where we are in this election, about how we will win in November," she said. "I am in this race because I believe I am the strongest candidate."
A delegate count by MSNBC gives Obama 1,880 delegates to Clinton's 1,718 with six more delegates to be awarded in West Virginia. That leaves him 145 short of the 2,025 needed to clinch the nomination.
Neither candidate can win without help from superdelegates - nearly 800 party officials who are free to back any candidate. Obama has been gaining ground among superdelegates for weeks and picked up four more on Tuesday.
"Barack Obama leads in pledged delegates, contests won and superdelegates. And for perspective, while 28 pledged delegates are up for grabs this evening, Obama has won the support of 27 superdelegates in the course of just the last week," an Obama campaign memo said.
According to the Times, Clinton loyalist James Carville now believes Obama will likely be the Democratic nominee.
In a speech at a South Carolina university, Carville said, "I think it's likely Obama is the nominee, but not certain. ... I would have preferred another result, but I'm going to be for him."
The newspaper quoted the outspoken strategist as saying, "Everybody is going to be with Obama," referring to Clinton's staff and backers. "I have an undated check written out for Obama. I'll send it when this is over."
Five more contests remain in the Democratic nominating battle, with a combined 189 delegates at stake. Oregon and Kentucky vote on May 20, Puerto Rico votes on June 1 and Montana and South Dakota vote on June 3.
Clinton is favoured again next week in Kentucky and Obama is favoured in Oregon.
