Clinton pushes on with uphill White House bid

By John Whitesides, Political Correspondent

WASHINGTON (Reuters) - Hillary Clinton's landslide West Virginia victory barely made a dent in Barack Obama's lead in the Democratic presidential race, but his renewed trouble winning white working-class support could raise warning flags for November.

Obama retains an almost unassailable advantage in delegates who will select the Democratic nominee at the party convention in August. He gained the support on Wednesday of two more superdelegates, who are free to back any candidate.

But exit polls showed Obama, who would be the first black U.S. president, won support from fewer than one-quarter of white voters without a college degree. That repeats a pattern seen in some other big Obama losses, including Ohio and Pennsylvania.

Clinton promised to push on through the last five contests. She hoped her 41-point blowout would spark a re-evaluation of Obama's candidacy and bolster her case that she is the Democrat with the best chance to beat Republican John McCain in November's election.

"I'm going to keep fighting until every last American has a chance to be heard, and as we learned last night in West Virginia, I know we can win," the New York senator and former first lady said on Wednesday in a plea for donations e-mailed to her supporters.

"I have the best chance of beating John McCain in November and putting America on the right track," said Clinton, whose campaign is at least $20 million in debt. She picked up the endorsement of one superdelegate on Wednesday.

Obama, an Illinois senator, headed to the general election battleground of Michigan on Wednesday and goes to Florida next week as he begins to turn his attention to a general election match-up with McCain, an Arizona senator.

He visited Warren, Michigan, outside Detroit to promote efforts to help the ailing manufacturing and U.S. car industry, including a $150 billion clean technologies venture capital fund to promote the production of fuel-efficient vehicles.