Conservative billionaire Charles Koch says that it's possible that he could support Hillary Clinton for president over any of the GOP presidential candidates.

In an interview in Kansas that aired Sunday on ABC's "This Week," Koch was asked if it's possible for another Clinton to be better than another Republican after he said President Bill Clinton "in some ways" was better than President George W. Bush.

"It's possible," Koch said.

Get Breaking News Delivered to Your Inbox

ABC's Jonathan Karl asked Koch, "You couldn't see yourself supporting Hillary Clinton, could you?"

"We would have to believe her actions would be quite different than her rhetoric. Let me put it that way," Koch said. "But on some of the Republican candidates we would, before we could support them, we'd have to believe their actions will be quite different than the rhetoric we've heard so far."

Koch said he probably won't support the GOP nominee because the candidates have been engaging in personal attacks rather than acting more like how Ronald Reagan explained how he would improve the country.

"Right off the bat, they didn't do it," he said. "More of these personal attacks and pitting one person against the other, that's the message you're sending the country."

Koch said that Donald Trump's proposal to ban Muslims from entering the U.S. was "antithetical to our approach" and he said that a proposal to make Muslims register is "reminiscent of Nazi Germany."

Asked to comment on Ted Cruz's comments about carpetbombing the Middle East, Koch said, "That's gotta be hyperbole, but I mean that a candidate, whether they believe it or not, would think that appeals to the American people. This is frightening."

Koch said if he controlled the Republican Party, the U.S. would not have a tax code that subsidizes the wealthy.

"We would get rid of all of that," he said.

But on Twitter Sunday afternoon, Clinton rejected a potential endorsement from the Koch brothers.

Not interested in endorsements from people who deny climate science and try to make it harder for people to vote. https://t.co/TWN4zYhMBh — Hillary Clinton (@HillaryClinton) April 24, 2016

In an interview with CBS News last October, Koch said "it depends" whether he plans to support anyone in the primary. He said, "I don't have the evidence that [the GOP candidates] are going to change the trajectory of the country."