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Cain: 'I am the Koch brothers' brother from another mother'

Herman Cain enthusiastically embraced the Koch brothers -- saying he is their "brother from another mother" -- just hours after facing a legal complaint challenging his campaign's ties to a Koch brother affiliated non profit.

"Just 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 during a speech at the Americans for Prosperity gathering in Washington, D.C. "Yes. I'm their brother from another mother! And proud of it!"

Cain said: "I'm proud to know the Koch brothers." He said a recent New York Times article made it sound like "we've had time to go fishing together, hunting together, skiiing together."

Charles and David Koch, whose company, Koch Industries, is one of the country's largest privately-held energy firms, have been major donors to conservative causes and, through their group, Americans for Prosperity, have been widely credited with helping to spur the emergence of the Tea Party. (David Koch was in attendance for today's speech.)

But Cain's ties to the Koch brothers and Americans for Prosperity have received new scrutiny this week. A watchdog group, the Citizens for Ethics and Responsibility in Washington (CREW), on Friday filed a legal complaint with the Federal Election Commission (FEC) charging that Cain and his campaign manager, Mark Block, violated election laws by using $40,000 in funds from a non profit founded by Block to pay for iPads and charter flights for Cain's presidential campaign.

Cain made his remarks Friday in direct reference to a story published Friday in the New York Times outlining those ties.

Non-profits are barred by law from spending money for presidential campaigns. Internal documents from the non-profit, Prosperity USA, were published this week by the Milwaukee Journal Sentinel. They contain apperent references to expenses paid by AFP on behalf of Prosperity USA and Cain -- "From AFP- H. Cain travel," one reads -- and an AFP spokesman this week confirmed the group was reviewing what it called "financial dealings" between the groups.

Asked about the FEC complaint filed by CREW, Cain campaign spokesman, JD Gordon, emailed Friday: "As with any suggestions of this type, we have asked outside counsel to investigate The Milwaukee Journal Sentinel's suggestions and may comment, if appropriate, when that review is completed."

The campaign finance allegations have added to Cain's problems this week. The candidate has found himself under siege this week for his acknowledgement of settlements that existed between two women and the National Restaurant Association related to allegations of sexual harassment brought against Cain during his time as the restaurant lobby's chairman. Cain did not address that controversy in his Friday speech.

The event was Cain's last in D.C., where he's spent most of the week. He's set to travel next to Houston, where he'll debate former House Speaker Newt Gingrich, a fellow Republican presidential hopeful.

GOP presidential candidate Herman Cain defends his ties to the Koch brothers, at the Americans for Prosperity Foundation, an organization funded by the Koch's.

NBC's Andrew Rafferty and msnbc.com's Michael O'Brien contributed.

Updated at 3:14 p.m.