By MATT APUZZO, Associated Press

Bill Richardson, the nation's only Hispanic governor, backed Barack Obama for president Friday, moved to deliver his much-coveted endorsement by the senator's speech about race.

The New Mexico governor joined Obama at a spirited rally Friday and said the Illinois senator demonstrated his leadership abilities this week with his speech on race. "You are a once-in-a-lifetime leader," the governor said from the stage. "Above all, you will be a president who brings this nation together."

Richardson dropped his own bid for the nomination in January. His support for Obama comes during a tough period for the senator. Although he still leads Hillary Rodham Clinton in delegates, Obama has seen his lead in national polls wither in the fallout from divisive remarks by his former pastor.

Richardson was relentlessly courted by both candidates and his support for Obama provides him a potential counterweight to Clinton's strength among Hispanic voters.

It was not the first time racial concerns had helped to drive a prominent backer to Obama. Massachusetts Sen. Edward Kennedy was moved to drop his neutrality and side with Obama in part because of what he saw as Bill Clinton's racially tinged criticisms of the senator.

Richardson heaped praise on Obama's speech about the nation's racial divide, the candidate's attempt to contain damage from his former pastor's comments.

"As a Hispanic-American, I was particularly touched by his words," Richardson said. "Senator Obama has started a discussion in this country that is long overdue and rejects the politics of pitting race against race."

The governor backed Obama despite his earlier statements that Democratic superdelegates, of which he is one, should pick sides based on the votes of their state or constituency. By that reasoning, he might have been expected to support Clinton because she won the New Mexico contest.

As a superdelegate, the governor plays a part in the tight race for nominating votes and could bring other superdelegates to Obama's side. He also has been mentioned as a potential running mate for either candidate.

No primaries are scheduled until Pennsylvania's on April 22, a gap Obama hopes to use for such announcements to assert that he is the front-runner for the nomination. Oregon hold its primary May 20.

Richardson backed Obama despite his ties to Clinton and her husband, the former president. Richardson served as ambassador to the U.N. and as secretary of the Energy Department during the Clinton administration. Last month, Richardson and former President Clinton watched the Super Bowl together at the governor's residence in Santa Fe.

Richardson praised Hillary Clinton as a "distinguished leader with vast experience." But the governor said Obama

The Clinton campaign publicly dismissed the endorsement, after the New York senator failed to win it for herself.

Citing Clinton's victory in New Mexico in February, senior strategist Mark Penn said, "Perhaps the time when he could have been most effective has long since passed."

Richardson bristled at that statement, which he said was a stereotypical suggestion that he was only valuable in states with large Hispanic populations. "will be a historic and great president, who can bring us the change we so desperately need by bringing us together as a nation here at home and with our allies abroad."Obama wants Richardson to help boost his foreign policy credentials, which Clinton has described as lacking.

Obama said Richardson "frankly has more concrete accomplishments on the international stage than my opponents, Democrat or Republican."

Richardson was a roving diplomatic troubleshooter when he was a congressman from New Mexico, negotiating the release of U.S. hostages in several countries and meeting a rogue's gallery of U.S. adversaries, including Saddam Hussein and Fidel Castro.

"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," Richardson said. "He showed this judgment by opposing the Iraq war from the start, and he has shown it during this campaign by standing up for a new era in American leadership internationally."

Obama embraced the endorsement of an accomplished figure who "understands the importance of restoring diplomacy as a central part of our national security strategy."

Both men have proposed negotiating with enemies as well as friends, while Clinton has emphasized the need to press for changes in repressive or hostile regimes before engaging with them at the presidential level.

There were also personal aspects to Richardson's swing behind Obama. He noted that both are the sons of one foreign-born parent Obama's father was from Kenya, Richardson's mother was from Mexico.

And Richardson told of the time, during one of the many Democratic debates, when his attention wandered and he did not hear the question that came at him. Obama, then his rival, bailed him out by whispering to him that it was about Hurricane Katrina.

"He could have thrown me under the bus," Richardson cracked, "but he stood behind me."

Among veterans of the once-crowded field of Democratic presidential hopefuls, Sen. Chris Dodd of Connecticut is the only other one who has taken a side so far. Dodd also endorsed Obama.

John Edwards, the strongest performer among the nomination dropouts, has also been wooed by Clinton and Obama but he has not announced an endorsement.

Associated Press Writer Barry Massey in Santa Fe, New Mexico, contributed to this report.