Senate Minority Leader Mitch McConnell appeared surprised Tuesday to learn that one a Republican senator challenged a labor leader to a fight at a committee hearing. 

The Kentucky Republican downplayed the notion that he’s able to ensure decorum at all times, on a day marked by several heated encounters between lawmakers in both chambers. 

“I hadn’t heard what you just indicated,” Mr. McConnell told reporters. “It’s very difficult to control the behavior of everybody who’s in the building. I don’t view that as my responsibility. That’s something the Capitol Police ought to deal with.”

The incident in question featured Sen. Markwayne Mullin, Oklahoma Republican, during a Senate Health Committee hearing Tuesday.

He challenged Sean O’Brien, leader of the International Brotherhood of Teamsters and a witness at the hearing, to a fight, only to be talked down by Chairman Bernard Sanders. 

“Sit down, sit down, you’re a United States senator!” Mr. Sanders, Vermont independent, shouted as Mr. Mullin rose from his seat.

Prior to Mr. Sanders intervening, Mr. Mullin and Mr. O’Brien exchanged schoolyard taunts as part of a long-running feud. 

“You want to run your mouth. We can be two consenting adults, we can finish it here,” Mr. Mullin said.

“Ok, that’s fine, perfect,” Mr. O’Brien responded.

“You want to do it now?” Mr. Mullin asked.

“I’d love to do it right now,” Mr. O’Brien replied.

“Stand your butt up then,” Mr. Mullin said.

“You stand your butt up,” Mr. O’Brien said.

Mr. Mullin, who is a former professional MMA fighter, stood and appeared to begin removing his wedding ring before Mr. Sanders stepped in. 

The event was one of at least three heated confrontations across the Capitol Tuesday involving lawmakers. The other two occurred in the House. 

• Ramsey Touchberry can be reached at rtouchberry@washingtontimes.com.