Charles Koch: Why I Didn't Try To Stop Donald Trump

— -- Charles Koch says he won’t “put a penny” into trying to stop Donald Trump, that there are “terrible role models” among the remaining Republican presidential candidates, and that his massive political network may decide to sit out of the presidential race entirely.

"These personal attacks and pitting one person against the other -- that's the message you're sending the country," Koch said in an exclusive interview with ABC News that aired Sunday. "You're role models and you're terrible role models. So how -- I don't know how we could support 'em."

The billionaire CEO of Koch Industries and one of the most powerful and controversial figures in politics said he and his brother David Koch have also turned down pleas to join the "Never Trump" movement, which aims to deny the real estate mogul the nomination.

Instead Koch said he and his brother plan to stay out of the party's nomination fight.

"We haven't put a penny in any of these campaigns, pro or con," Koch said. "That's not what we do. What we're trying to do is build alliances to make the country better.”

Koch, author of the book "Good Profit," said he would only consider contributing to either Trump or Cruz if they backtrack on some of their most controversial promises. That includes one of Cruz's favorite lines of his campaign stump speech -- to carpet bomb ISIS in the Middle East and "make the sand glow."

"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," Koch said. "This is frightening."

Koch also slammed Trump's rhetoric towards Muslims, saying his proposal of a temporary travel ban was "antithetical."

"What was worse was this 'we'll have them all registered,'" Koch said. "That's reminiscent of Nazi Germany. I mean -- that's monstrous as I said at the time."

Koch went so far as to say the GOP nightmare of another Clinton presidency might be a better alternative to the remaining Republican candidates at this point.

"It's possible," he said.