Hours after facing a complaint about allegedly illegal contributions to his campaign by a nonprofit organization affiliated with the billionaire Koch brothers, Republican presidential hopeful Herman Cain made clear that he is "very proud to know the Koch brothers."

The complaint was filed Friday with the Federal Election Commission by the Citizens for Responsibility and Ethics consumer group, Reuters reported.

"[J]ust so I can clarify this for the media -- this may be a breaking-news announcement for the media -- I am the Koch brothers' brother from another mother," Cain said Friday during a speech at an Americans for Prosperity event in Washington. "Yes, I'm their brother from another mother. And proud of it."