Billionaire businessman David Koch has helped direct millions to Republican candidates but he disagrees with the party on gay marriage.

The Libertarian-minded Koch -- whose brother, Charlie, also is a big GOP supporter -- made the remarks Thursday on the sidelines of the Republican National Convention.

"I believe in gay marriage," the 72-year-old Koch told Politico. He was in Tampa as a New York delegate and to attend an event held by Americans for Prosperity -- the political advocacy group he helps fund and lead.

He also told the newspaper the U.S. military should withdraw from the Middle East and that the federal government should consider tax increases and defense-spending cuts to improve fiscal woes.

Despite the apparent break from several traditional GOP positions, Koch said he considers himself foremost a Republican, not the Libertarian he was in the 1980s.

He said he quit the Libertarian Party because it had "gone too far off the deep end" but supports the Republican Party because it has "a great chance of being successful."

-- Joseph Weber