An Oklahoma senator challenged a union president to a fight during a Senate hearing last night.
Republican Senator Markwayne Mullin rose from his seat, before the committee chair stepped in defuse the confrontation.
The verbal sparring began after Mr Mullin paraphrased from a June tweet posted by Teamsters President Sean O'Brien about the Senator: "...what a clown, a 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."
Mr Mullin finished with an offer to fight Mr O'Brien at the hearing, saying: "Sir, this is a time, this is a place, if you want to run your mouth, we can be two consenting adults, we can finish it here," while pointing to the floor separating the two.
Mr O'Brien responded: "Okay that's fine, perfect."
Mr Mullin then rose for his seat after Mr O'Brien said "you stand your butt up, big guy" as the two traded further barbs.
At that point, Senator Bernie Sanders, who was chairing the hearing with union presidents, said to Mr Mullin: "You're a United States senator, sit down."
Mr Mullin again later in the hearing challenged Mr O'Brien to fight for charity in April.
