Conservative billionaire, Charles Koch said on Monday that he doesn’t plan on supporting Donald Trump because his principles are “antithetical” to his.

During an interview at the Fortune Brainstorm Tech conference in Aspen, Colorado, Koch said of the two presumptive presidential nominees: “I see two people that as of this point we’re not supporting.”

“If I had to vote for cancer or a heart attack why would I vote for either?” Koch said.

Charles and his brother David Koch have been major donors to the GOP and their choice not to support Trump can have major repercussions to the Republican Party.

“I’m sure he’s a fine fellow underneath but when you look at our guiding principles, his guiding principles are in many ways antithetical to ours.” Koch said about Trump.

Koch has criticized Trump’s plan for taxes on certain imports, claiming that it was that kind of action that led to the Great Depression of the 1930s.

When he was asked about a previous comment he made about backing Hillary Clinton, he claims that he was misinterpreted.

“What I said was it was possible (to back Clinton) if she totally changed everything she stood for,” he said.

“I have got to be more careful about what I say.”

The Koch brothers, whose industries are the second largest in the United States, continue to fight for minimizing the government, lowering taxes and eliminating regulations.