Former US presidential candidate John Edwards endorsed Democrat Barack Obama on Wednesday, giving a major boost to the Illinois senator's effort to unify the party behind his bid for the White House.
Edwards, the 2004 vice presidential nominee, had been heavily courted by both Obama and rival Hillary Clinton.
"The reason I am here tonight is the Democratic voters in America have made their choice and so have I," Edwards, who dropped out of this year's Democratic race in January, said at a rally with Obama in Grand Rapids, Michigan.
"There is one man who knows in his heart that it is time to create one America, not two, and that man is Barack Obama," he said, as Obama sat on a stool behind him.
The long-awaited endorsement helped blunt the impact of Clinton's landslide 41-point win over Obama in West Virginia on Tuesday. That result barely put a dent in Obama's lead in the Democratic race for the right to face Republican John McCain in November's presidential election.
Obama has an almost unassailable advantage in delegates who will pick the nominee at the party's convention in August, and has turned his attention to a general election match-up with McCain for the past week.
"I have no doubt that John Edwards can be extremely helpful to us campaigning in every demographic," Obama told reporters on his plane, adding that he hoped to get Edwards' delegates, estimated to number about 18, as well.
He said Edwards would "be on anybody's short list" for the vice presidency but said further comment would be premature.
Obama gained the support of four more superdelegates -- party officials free to back any candidate -- as well as the abortion rights group NARAL Pro-Choice America on Wednesday.
Edwards praised Clinton's "strength and character" but said it was time for Democrats to unite against McCain. He called Obama on Tuesday night to tell him he was ready to make the endorsement, an Obama aide said.
The backing of Edwards could help Obama attract white working-class voters who have flocked to Clinton in recent contests. The former North Carolina senator made a populist economic agenda on behalf of lower and middle income workers a centerpiece of his presidential bid, and has focused heavily on efforts to battle poverty.
Obama, who would be the first black U.S. president, won the votes of fewer than one-quarter of whites without college degrees in West Virginia, exit polls showed, similar to his showing in other states.
Clinton's campaign shrugged off the endorsement.
'Far from over'
"We respect John Edwards, but as the voters of West Virginia showed last night, this thing is far from over," her campaign chairman, Terry McAuliffe, said in a statement.
The New York senator spent Wednesday in Washington doing media interviews and meeting with donors. She promised to keep running until the last of the five remaining state contests concludes on June 3.
"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's campaign is $20 million in debt but 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 nomination. To win, both need superdelegates, with whom Obama has been gaining ground for weeks.
He also picked up the backing of three former chairmen of the Securities and Exchange Commission, including William Donaldson, who was appointed by 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. Focusing on November's contest with McCain, Obama 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 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 in Michigan 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.
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.