Republican presidential candidate Herman Cain expressed his fondness for Charles and David Koch on Friday while appearing at an event partially funded by the billionaires.

"There was an article in The New York Times today that has attempt to attract some more attention [to me]," Cain told a crowd at American for Prosperity's Defending the American Dream Conference. "The article tries to make a case of how close the Koch brothers and I are."

"I'm proud to know the Koch brothers. I'm very proud to know the Koch brothers," the candidate said. "They make it sound like we've had time to go fishing together, hunting together, skiing together, golfing together."

Cain added: "Just so I can clarify to the media -- this may be a breaking news announcement for the media -- I am the Koch brothers' brother from another mother! Yes, I'm their brother from another mother! And proud of it!"

On Friday, Citizens for Responsibility and Ethics in Washington (CREW) filed a complaint with the Federal Election Commission (FEC) over allegations that Prosperity USA had illegally funneled donations to the Cain's campaign through Americans for Prosperity. At the time, Prosperity USA, the Wisconsin arm of Koch-backed Americans for Prosperity, was operated by Cain campaign manager Mark Block.

"It is not sufficient for the Cain campaign to investigate itself," CREW executive director Melanie Sloan said in a media advisory. "Rather, the FEC -- the federal agency charged with enforcing campaign finance laws -- must look into the matter."

Cain first met Block while working as a speaker for Americans for Prosperity in 2005.

Watch this video from CNN, recorded Nov. 4, 2011.