At a lively rally at Memorial Coliseum in Portland, Ore., Gov. Bill Richardson, D-N.M., officially endorsed Sen. Barack Obama, calling the presidential hopeful a "once-in-a-lifetime leader" who would be "a president who brings this nation together."
The coveted endorsement was a badly needed shot in the arm after days of unwanted headlines.
Richardson Backs Obama, Rebuffs Clintons
Richardson, a former Clinton Cabinet member, insisted, "My great affection and admiration for Hillary Clinton and President Bill Clinton will never waver," but he added, "It is time, however, for Democrats to stop fighting among ourselves and to prepare for the tough fight we will face against John McCain in the fall."
Energy secretary and U.N. ambassador during the Clinton administration, Richardson is known to have maintained a close relationship with Bill Clinton.
The former president even flew to New Mexico to watch the Super Bowl with his former Cabinet member, a trip that was ultimately to no avail.
"I talked to Senator Clinton last night. Let me say I've had better conversations," Richardson joked at the time.
Vouching for Obama's National Security Credentials
The New Mexico governor and one time United Nations ambassador expressed confidence in Obama's ability to navigate potential national security crises, an area in which Sen. Hillary Clinton has repeatedly attacked Obama.
"There is no doubt in my mind that Barack Obama has the judgment and courage we need in a commander in chief when our nation's security is on the line. . . "You will be an outstanding commander-in-chief," Richardson said.
Obama responded that he was "deeply honored" by the governor's support.
"Whether it's fighting to end the Iraq War or stop the genocide in Darfur or prevent nuclear weapons from falling into the hands of terrorists, Gov. Richardson has been a powerful voice on issues of global security, peace and justice, earning five Nobel Peace Prize nominations," the Democratic front-runner said.
Good News in Tough Week
Richardson's endorsement could not have come at a better time for Obama.
After a political week dominated by controversy surrounding his pastor, Reverend Jeremiah Wright, Obama needed some positive news.
"We had a couple tough weeks and I assume when I am president, I assume there are periods where we are tested in these same ways," Obama said at a press conference following the endorsement rally.
"Coming off the fence shows other superdelegates that you can go against the Clintons even if they've helped you become a national figure or even if they've helped you in your career," ABC News political consultant Mark Halperin said of the endorsement.
Fierce Fight as Obama Camp Gets Tough
Senator Obama, for his part, stayed above the fray, leaving the fierce Democratic party in-fighting to his campaign manager, who earlier in the day had assailed Hillary Clinton's "character gap".
"She is not seen as trustworthy by the American people. She has consistently, in this campaign, engaged in political miscalculation to mislead voters," David Plouffe, Obama's campaign manager said on a conference call with reporters on Friday.
The Clinton campaign responded in a call of its own.
"The Obama campaign is in political hot water given the news stories of the last couple weeks and is basically desperate to change the subject," fired back Clinton campaign spokesperson Phil Singer.
The nastiness between Obama and Clinton is having an impact. Polls indicate a sizeable minority of Clinton supporters have developed resentments toward Obama and vice versa.
"Intensity matters and it just takes a few percentage of voters to sit on their hands, stay at home, and not vote at all or switch sides and vote for John McCain and that could cost you a swing state like Ohio or even Pennsylvania," said Jay Carney, deputy bureau chief for TIME magazine in Washington.
Hispanic Guv Could Help With Key Group
Richardson, the nation's only Hispanic governor, has been actively courted by both campaigns since he abandoned his own bid for the White House in January, after poor showings in both the Iowa caucuses and New Hampshire primary.
In his endorsement, Richardson called Obama a friend, noting such personal similarities as their mixed ethnic identity. Both he and Obama have one foreign-born parent. Richardson's mother was from Mexico, and Obama's father was from Kenya.
Richardson also said Obama's race speech resonated with him as an ethnic minority.
"As a Hispanic, I was particularly touched by his words. I have been troubled by the demonization of immigrants -- specifically Hispanics -- by too many in this country," he said.
Richardson also recounted a story from the days when he was still a presidential candidate.
He recalled that during one debate, he was not paying attention to a question asked of him by the moderator. Obama, then still a rival for the nomination, was seated next to him and whispered, "Katrina, Katrina."
"He could have thrown me under the bus," Richardson laughed. "But he stood behind me."
Obama's Communications Director Robert Gibbs said that Obama spoke with Richardson weekly over the telephone, but while visiting Richardson's home state last month, Obama told reporters that he was not necessarily expecting the governor's endorsement.
"We have no plans of receiving an endorsement, but I would love to be pleasantly surprised. I've had many conversations with Gov. Richardson and I'm sure the Clinton campaign has. He is obviously a tremendously important leader in the country. He ran a terrific race this presidential season, and I think would make an enormous contribution to any candidate whom he chose to support," Obama said at the time.
Clinton Camp Downplays Impact
Friday the Clinton campaign appeared to downplay the significance of the coveted endorsement, with senior strategist Mark Penn pointing out Clinton's victory in New Mexico.
"Perhaps the time when he could have been most effective has long since past," Penn said, dismissing the practical value of Richardson's support after the New Mexico primary.
Richardson had stipulated two necessary criteria for a candidate to receive his endorsement.
In February, Richardson told The New York Times that the candidate should reflect the vote of his state and constituency. But he had also said the candidate with the most delegates after the March 4 primaries should be the Democratic nominee.
Though Clinton won the New Mexico primary, she won by only a very slim margin, and Obama still continues to have the lead in total delegates.
Richardson is the second former presidential candidate to endorse Obama.
Sen. Chris Dodd of Connecticut also endorsed the Illinois senator.
ABC News' Sarah Amos and The Associated Press contributed to this report.