“Let’s start with the obvious — a tyrant sits in the White House,” Walsh added. “The very thing our Founders feared most is here. Throw in the fact that one of our two major political parties is a real and direct threat to democracy and the rule of law. These are unprecedented, dangerous times in America. I know it. You know it. There are even Republicans who know it.”
There’s a bunch of articles about it, he’s talked about it. He donated to them, and opened his networks up to their usage/advertising:
https://www.google.com/search?q=Koch+supports+democrats
Charles Koch says he’d work with Democrats who share his values
Sure, he’ll support Democrats as long as they have Republican values.