Former Sen. John Edwards, D-N.C., endorsed Sen. Barack Obama, D-Ill., for president in a dramatic attempt to help Obama answer concerns about his lack of support from white, working-class voters.
The move is seen as a major blow to Sen. Hillary Clinton, D-N.Y., who has rebranded herself during the course of the presidential campaign as a fighter for the working-class.
"I am fired up!" a beaming Obama told a large crowd at a campaign rally in Grand Rapids, Mich., Wednesday night.
Saying he felt bad about not being able to campaign in Michigan prior to now, Obama said he wanted to give voters in Michigan something special and introduced "my friend, John Edwards."
After walking out to an ecstatic crowd and to Bruce Springsteen's "The Rising," Edwards said, "During the course of this presidential campaign I have gotten to know the presidential candidates very, very well," he said. "Now, we're here, down to two amazing candidates."
Before explaining his decision, Edwards was booed by the crowd when he said he wanted to talk about "our friend, Sen. Hillary Clinton."
"What I've learned, and I've gotten to know her very well, is that she believes with every fiber of her being that America can be a better place and that we need change," he said.
"It is very, very hard to get up every day and do what she's done," he said. "It is hard to go out there and fight and to speak up when the odds turn against you ... what she has shown is strength and character ... she cares deeply about the working people in this country.
"She is a women who, in my judgment, is made of steel," he said. "And she's a leader in this country, not because of her husband, but because of what she has done."
After praising Clinton to meek applause, Edwards began explaining why he's decided to back Obama.
"Americans have made their choices and so have I. ... There is one man that knows and understands that this is a time for bold leadership ... there is one man who knows in his heart that it is time to create one America -- not two, and this man is Barack Obama."
Edwards said the Illinois senator stands with him in a fight to cut poverty in half within 10 years.
An Edwards aide told ABC News' Raelyn Johnson that it was only in the last day or two that Edwards made up his mind to endorse Obama, citing the fact that the race is over and the Democratic Party needs to focus on the fall.
'Clearly a Very Difficult Decision'
Mark Kornblau, a former Edwards aide, told ABC News that Edwards' decision to endorse was not easy and that he continues to have great admiration for Sen. Clinton.
"The reason that he's doing this is that he thinks Sen. Obama is going to be a great president," said Kornblau, who said he spoke to Edwards hours before his announcement. "He's going to be a great candidate for the Democratic Party and ... it's time for the party to unite around Sen. Obama and focus on winning in the fall."
Kornblau says indecision was a factor in Edwards' timing, which was seen by some as sluggish.
"I think it was clearly a very difficult decision and that's part of the reason that he waited for so long," Kornblau said. "But it's now become clear that Sen. Obama is going to become the nominee and Sen. Edwards feels that it's important that the party rally around the nominee [and] focus on beating John McCain in the fall."
Blue Collar Clinton
The announcement also came after Clinton's 41-point victory in the West Virginia Democratic primary Tuesday.
Her ability to continuously attract broad support from key demographics -- white, lower-income, low education voters in Southern states -- has fueled questions about Obama's viability in the general election.
Clinton's decision to do television interviews with all the network anchors Wednesday afternoon may have been an attempt to parlay her overwhelming West Virginia primary victory into a news cycle of mini-momentum, and possibly to raise some badly needed cash off of it.
Edwards, who ran for president on a platform of eradicating poverty, enjoyed the support of many white, Southern, working-class voters before he stepped out of the race on Jan. 30. He and his wife Elizabeth, who is battling cancer, have remained neutral until this announcement.
Tad Devine, a Democratic strategist and former chief political consultant to Al Gore's 2000 presidential campaign, believes the Edwards endorsement could boost Obama's popularity among those in this key demographic.
"I think in this election, white working class voters are going to be one of the key voting blocks," Devine said. "And for Sen. Obama to be able to persuade them to support him could be one of the big keys to the election. And I think having support from John Edwards now, and having support from the entire Democratic Party later, is going to be one of the ways that Sen. Obama begins to break through with those voters where he hasn't done as well as Hillary Clinton."
Devine also thinks voters can expect to see Edwards campaign for Obama in key states.
"I think Sen. Obama wants to send John Edwards out to campaign for him in places like Kentucky immediately, particularly rural communities where John Edwards is so well liked and pretty well known," he said. "I think you want him campaigning for you in places like Montana and South Dakota as well ... and he can also represent Barack Obama nationally."
Mark Kornblau agrees.
"[I] think Sen. Obama would be wise to use Sen. Edwards in the general election aggressively, particularly in some of the rust belt states in the upper Midwest where he is enormously popular," he said. "And he really connects with working class voters in states like Wisconsin, Minnesota, in rural and even urban parts of Ohio."
While endorsements aren't thought to carry much sway with voters, Edwards' support will give Obama a key stamp of approval as he attempts to clinch his party's nomination.
Both candidates had actively persued Edwards' support, even traveling separately to Edwards' home in Chapel Hill, N.C., to personally ask for his support.
Only the backing of former Vice President Al Gore was more coveted by Obama and Clinton.
Today's endorsement also raised questions regarding Edwards possibly positioning himself as Obama's potential running mate, but Kornblau is dubious.
"Having lived through it before, I don't think Sen. Edwards is interested in being a vice presidential candidate or a vice president, but I'm sure he is going to do whatever Barack Obama asks him to do to help him win in the fall," he said.
Elizabeth Edwards Not Part of Endorsement
Edwards' dramatic, nationally televised announcement comes on the heels of 48 hours of an intense media spotlight, and much discussion, since the April 22 Pennsylvania primary focused on Obama's apparent troubles wooing white working-class voters to his campaign in large numbers.
Edwards may be seen as a high profile validator for Obama with those voters.
His wife, Elizabeth, has yet to endorse any candidate. Edwards insiders said she is not part of her husband's announcement.
"I would not endeavor to try to speak for Elizabeth Edwards, having not spoken to her," said Kornblau, "But she has been fairly clear since Sen. Edwards dropped out that she's not going to endorse until the party has decided on a nominee. So she stayed true to her word today and Sen. Edwards was out there supporting Sen. Obama. "
Elizabeth, in the past, has said she would not necessarily feel obliged to support the same candidate her husband chose to support. She's been on the record endorsing Clinton's health care plan over that of Obama's.
Clinton Camp Brushes Off Endorsement
Clinton advisors publicly dismissed Edwards' endorsement Wednesday.
"We respect John Edwards, but as the voters of West Virginia showed last night, this thing is far from over," said Clinton campaign chair Terry McAuliffe.
A source close to the Clinton campaign said the Edwards camp gave the Clinton folks a heads up, reports ABC News' Kate Snow.
"Well, I don't think it's good news, but there's a lot of news in this business and we move forward and move past it. It's not great news," a Clinton senior advisor told ABC News.
Asked what effect the Edwards endorsement might have, the advisor said, "We don't know. We'll see. We'll see how much of it is transferable," referring to Edwards' popularity with white working-class voters.
"We would've preferred it [to be our endorsement]," the advisor said. "That's not a secret."
Clinton met Wednesday with six uncommitted superdelegates at the Democratic Congressional Campaign Committee offices in Washington.
This advisor said the Clinton campaign believes superdelegates are concerned about Obama's loss in West Virginia last night and other swing states.
"No question -- that started with Ohio and increased with Pennsylvania, Indiana and West Virginia," he said. "All I can say is, I don't want to overdramatize it, but starting with Ohio, the remaining superdelegates started really focusing on the 270 electoral vote issue, and how do we best assemble that, and it's made a marked impression."
But then, in a moment of candor, the advisor conceded, "I'm not sure it's gonna be enough."
At about the same time Edwards will endorse Obama, Clinton supporters on the Hill will try to get some attention holding an event to tout what they call her "strong pro-choice record."
It's a reminder that Obama has taken, not one, but two surprise endorsements. Not only is Edwards staging an endorsement just in time for the evening news, but the pro-abortion rights group, NARAL, endorsed Obama earlier Wednesday.
Clinton supporter Ellen Malcolm of EMILY'S LIST called that NARAL endorsement "tremendously disrespectful" of Clinton.
ABC News' Kate Snow, Raelyn Johnson, Eloise Harper, David Chalian, Sunlen Miller, Eric Johnson and Rick Klein contributed to this report.