WASHINGTON — Kentucky Gov. Matt Bevin called California Lt. Gov. Gavin Newsom a "dirtbag," a "joke" and an "embarrassment to public service" at a private meeting of the Koch political network Monday in Colorado Springs, Colorado, according to one person in attendance.

Bevin, a Republican, was making the case for members of the wealthy donor group to support John Cox, who is Newsom's opponent in California's gubernatorial race.

"That guy's a joke," Bevin said of Newsom, according to a person who attended the panel discussion at which Bevin spoke, who asked not to be identified because they were not authorized to discuss it.

"He’s an embarrassment to public office," Bevin said. "His personal life, his professional life has a wake of disaster behind it, and the idea that he’s somebody that anybody would believe is worthy of carrying the torch of the sixth-largest economy in [the world] is an insult to everybody who does live in California and everybody who lives in America."

Though Bevin didn't specify which parts of Newsom's personal or professional lives he was referring to, critics often point to Newsom's one-time affair with his then-campaign manager's wife, who also worked for him, and subsequent announcement that he was seeking help for an alcohol problem. He has been married to his second wife, Jennifer Siebel, for a decade, and the couple has four children. He was previously married to former Fox News personality Kim Guilfoyle, who is now dating Donald Trump Jr.

Bevin went on to say that Newsom isn't very popular in his own party.

"There's a whole lot of Democrats, liberals included, who don't think very highly of Newsom, who find him to be the squirrelly little weasel that he is," Bevin said. "The guy's a dirtbag."

Newsom's campaign didn't immediately respond to a request for comment sent via direct message to an aide.