In 2004, Mayweather was convicted on two counts of battery for punching two women at a Las Vegas nightclub the previous year. He was given suspended prison sentences, $1,000 in fines and ordered to complete impulse control counseling.

Mayweather in 2002 pleaded guilty to two counts of domestic violence in one case and battery in another. In 2005, a jury acquitted him of a third domestic violence charge, a felony, after his accuser changed her story. He reportedly was convicted of battery in his hometown of Grand Rapids, Mich., and he has also been the subject of civil lawsuits accusing him of battery.

An Obama spokeswoman said Mayweather has paid for what she termed his "mistakes."

"Like many, Floyd Mayweather has made mistakes in his life," Shannon Gilson said. "He has made strides to atone for those mistakes and is an important member of the community through his philanthropy and work with schoolchildren in Las Vegas."

On Monday, Obama's Nevada campaign issued a news release headlined "Barack Obama Campaign to Launch African Americans for Obama with Floyd Mayweather." But when asked about Mayweather's criminal record, the Illinois senator's campaign downplayed the fighter's role in the event.

"This is not about Floyd Mayweather, this is about the growing grass-roots support for Barack Obama in the African American community," Gilson said. "This story for us is really about grass-roots activism, and it's a shame that's not going to be the focus."

Also scheduled to attend the launch event at downtown's Ice House Lounge are Obama senior adviser Mike Strautmanis, Nevada state Sen. Steven Horsford, Assemblyman Kelvin Atkinson and state lobbyist Rose McKinney-James.

University of Nevada, Reno, political scientist Eric Herzik said the Obama campaign made a bad choice in associating itself with someone with such a dicey past.

"You're dealing with legal problems, and domestic violence in particular," he said. "No candidate wants to be associated with that. You'd think his staffers would have raised a red flag about this."

Candidates, he said, should be careful which stars they pick to lend their glamor to the campaign. "There are plenty of sports stars you wouldn't want to tap (for support). There are plenty of celebrities you might think twice about," he said, mentioning Mel Gibson and Britney Spears as examples.

Especially in today's political atmosphere, campaigns should expect such scrutiny, Herzik added. "Hillary Clinton had to give back more than $800,000 because a donor was arrested who just collected money for her," he said, referring to the scandal involving contributions solicited for the New York senator's campaign by former fugitive Norman Hsu.

"Candidates want to be above reproach," he said.

Mayweather's manager, Leonard Ellerbe, said the fighter's association with Obama was purely unofficial. "He is a fan who admires the senator's accomplishments," Ellerbe said. Mayweather does not get involved in politics or make endorsements, he said.

It wasn't clear how Mayweather came to be part of the event. Ellerbe would not explain how Mayweather's name came to be on the news release.

"Nobody approached anybody," he said. "Floyd was not solicited by the campaign, and Floyd did not solicit the campaign."

Ellerbe said Mayweather, who was voted off "Dancing With the Stars" last week, was focused on training for his Dec. 8 welterweight fight with Ricky Hatton at the MGM Grand.

Often termed the best pound-for-pound fighter in the world, Mayweather's "Pretty Boy" nickname comes with a reputation for brash trash-talking. His May fight against Oscar De La Hoya, also at the MGM, was the top-grossing boxing match of all time. Cast as the bad guy in contrast to De La Hoya's sweetheart image, Mayweather was booed as the judges announced their decision that he was the winner.

Ellerbe pointed out that Mayweather does charity work in the community, including adopting schools and feeding the homeless, work he "doesn't seek media attention for."

As for the criminal charges, Ellerbe said, "I won't even address something negative, because we're all about doing positive things for the community and the world."

Mayweather and Obama, he said, are "two young men who happen to be African Americans at the top of their careers in their respective fields."

Review-Journal writer David Kihara contributed to this report.