Edwards to endorse Obama's White House bid

He gained the support on Wednesday of four more Democratic superdelegates, nearly 800 party officials who are free to back any candidate, as well as the abortion rights group NARAL Pro-Choice America.

Obama’s camp hopes the endorsement by Edwards, a former North Carolina senator, will help his effort to win over white working-class voters who were among the core constituents of Edwards during his presidential bid.

Edwards made a populist economic agenda on behalf of lower and middle income workers a centrepiece of his campaign and has focused heavily on efforts to wipe out poverty in the United States.

Obama, who would be the first black U.S. president, won fewer than one-quarter of whites without college degrees in West Virginia, exit polls showed, similar to other states.

Clinton, who spent Wednesday in Washington doing a round of media interviews and meeting with top donors, promised to push on through the last five of the state-by-state contests.

"We don’t have a nominee yet and until we do, I’m going to be making my case," she said on Fox News.

CLINTON IN DEBT

Clinton’s campaign is $20 million (10.3 million pounds) in debt but her campaign chairman, Terry McAuliffe, said she had the resources to compete with Obama and described her donors as "very excited, ready to go and ready to help."

Clinton added one superdelegate endorsement on Wednesday.

A delegate count by MSNBC gives Obama 1,885 delegates to Clinton’s 1,722 -- both short of the 2,025 needed to clinch the Democratic nomination.

Neither can win without help from superdelegates.

Obama has been gaining ground among the superdelegates for weeks. He also picked up the backing of three former chairmen of the Securities and Exchange Commission, including William Donaldson, an appointee of Republican President George W. Bush.

Obama spent the day in Michigan, where he touted plans for a $150 billion clean technologies fund to create new jobs and promote fuel-efficient vehicles.

He looked past the race with Clinton to focus on a November match-up with McCain. He said the Arizona senator "is not offering new solutions or economic policies that are different from what George Bush has given us for eight long years."

Obama’s visit to Michigan was his first trip there since he signed a pledge last year promising not to campaign in the state because of its dispute with the national party over the timing of its primary election.

Clinton won the Michigan contest and Obama’s name was not on the ballot. She also won a disputed race in Florida and is pushing for delegates from both states to be seated at the convention.

Obama has said he wants the delegates seated fairly.

"We feel very confident about our ability to win Michigan. Now obviously because of the whole hoopla around when Michigan held its primary, my name was not on the ballot and we did not do campaigning here," Obama said. "That wasn’t my choosing."

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 on June 1, and Montana and South Dakota on June 3.

Clinton is favoured in Kentucky and Obama has been leading in the polls in Oregon.

(Additional reporting by Andy Sullivan, Ellen Wulfhorst and Jeff Mason; Editing by John O’Callaghan)