WASHINGTON (KFOR) – Oklahoma Senator Markwayne Mullin (R) had a heated exchange with International Brotherhood of Teamsters General President Sean O’Brien during a hearing on Tuesday.

The argument took place in the Senate Health, Education, Labor and Pensions Committee room. The confrontation prompted Chair Bernie Sanders (I-Vt.) to step in.

During the argument, Sen. Mullin read aloud social media posts where O’Brien called him a “clown” and a “fraud”, according to officials.

“Sir, this is a time, this is a place. You want to run your mouth, we can be two consenting adults, we can finish it here,” Mullin said.

“OK, that’s fine. Perfect,” responded O’Brien. 

“You want to do it now?” Mullin asked. “Stand your butt up then.” 

The Hill says Mullin then stood up from his chair, which prompted Sanders to step in and take control of the situation.

This comes after a previous argument the two had in June, where O’Brien tweeted about Mullin several times, including a tweet that reads, “Greedy CEO who pretends like he’s self made. In reality, just a clown & fraud. Always has been, always will be. Quit the tough guy act in these senate hearings. You know where to find me. Anyplace, Anytime cowboy. #LittleManSyndrome”.

Sen. Mullin replied five days later with a challenge to an MMA fight.

“An attention-seeking union Teamster boss is trying to be punchy after our Senate hearing. Okay, I accept your challenge. MMA fight for charity of our choice. Sept 30th in Tulsa, Oklahoma. I’ll give you 3 days to accept.” Mullin said.