'He's a thug!' GOP senator has no regrets about challenging Teamsters boss to a fight

Sen. Markwayne Mullin (R-OK) isn't backing down after literally trying to pick a fight with Teamsters President Sean O'Brien.

In an interview with CNN's Manu Raju after he challenged O'Brien to physically fight him during a heated Senate hearing, Mullin said he had no regrets about how he handled the situation.

"He's a thug!" Mullin said of O'Brien, who has verbally sparred with the Oklahoma Republican in past hearings. "He's been running at the mouth forever."

Mullin also claimed that it was O'Brien who started the dispute.

"He called me out," Mullin said. "I was just answering the call. Don't say something you're not going to back up. It's that simple. He's a president of a union. I'm still a guy from Oklahoma.”

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Mullin also said that he was "raised different" when it comes to being willing to physically fight people over political disagreements, while against emphasizing that witnesses in Senate hearings shouldn't "say something stupid like that unless you're going to truly back it up."

Sen. Bernie Sanders (I-VT), who was chairing the hearing on the labor movement in the United States, admonished his Republican colleague for expressing a desire to fight a witness.

"Sit down," he said. "You're a United States Senator. Act like it."