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Teamsters president Sean O’Brien, who almost came to blows with an Oklahoma senator, has deep Mass. ties.

Sean O'Brien, General President of the International Brotherhood of Teamsters, testified during a Senate Health, Education, Labor and Pensions Committee hearing on unions on Tuesday in Washington, D.C.Kevin Dietsch/Getty

Teamsters president Sean O’Brien made headlines Tuesday when Senator Markwayne Mullin, an Oklahoma Republican and former mixed martial arts combatant, challenged him to a fight during a tense committee hearing on Capitol Hill.

But those watching the belligerent exchange might not have known that O’Brien, 51, has deep Massachusetts ties.

The Medford native is a former heavy-equipment driver who led the Local 25 union in Charlestown for 15 years. His family has been involved with the Teamsters for four generations, according to a previous Globe profile. His great-grandfather made deliveries around Boston in a horse-drawn wagon, his grandfather was a truck driver and later a business agent for Local 25, and his late father was a transportation coordinator for the union’s motion picture division. Three of his uncles have been involved in Local 25, and his older and younger brothers are also members.


O’Brien was a linebacker and captain of the football team at Medford High School and made the statewide Shriners all-star team. But success on the field didn’t come easy.

“I wasn’t the most gifted athlete, so I was always working harder after practice in the weight room,” he told the Globe in an interview earlier this year.

O’Brien worked for Local 25 in high school unloading trucks for concerts and Broadway shows. He went to the University of Massachusetts Boston but quit after one semester to go to work hauling heavy equipment. “I loved being a Teamster,” O’Brien said.

Within a few years, he was a shop steward, serving as a union representative for fellow workers. In 2006, at the age of 34, O’Brien became the youngest president in the history of Local 25, which currently represents more than 12,000 members in Boston and Southern New England.

His talent for the work, and hard-nosed tactics, showed early. Tim Madden, a retired UPS driver and former shop steward in Watertown, attended grievance hearings with O’Brien and said he had a knack for finding a supervisor’s weakness and using it against him.


“Sean always says, the way to take on the schoolyard bully is get right in his face and stare him down,” he said.

He was also always prepared, well dressed, and hours early, Madden said. “Sean dots every ‘i’ and crosses every ‘t’ himself,” he said. “The man does not make mistakes.”

O’Brien’s clash with Mullin came during a hearing before the Senate Committee on Health, Education, Labor & Pensions and may have gotten physical but for the intervention of Senator Bernie Sanders, himself known for rhetorical pugnacity.

Mullin, 46, noted that O’Brien had insulted him several times on social media, calling him a “greedy CEO who pretends like he’s self-made,” as well as a “clown” and a “fraud.”

“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 to O’Brien, a witness at the hearing.

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

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

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

At that point, Mullin, a married father of six, sprang from his chair and even adjusted his wedding ring as if preparing to remove it for a bareknuckle scrap, while others could be heard yelling.


Sanders quickly interceded, telling Mullin to “hold it” and “sit down.”

“No, no, no, sit down. Sit down! You’re a United States senator, sit down,” Sanders said. He banged his gavel.

“This is a hearing. God knows the American people have enough contempt for Congress, let’s not —” Sanders yelled before he was cut off by Mullin and O’Brien, who continued exchanging barbs.

“We’re not here to talk about physical abuse,” Sanders said after Mullin challenged O’Brien again.

Mullin later told CNN that he has “no regrets” about what happened and that he was “raised different” when pressed about the propriety of settling disputes physically. “He’s a thug,” he said of O’Brien.

O’Brien also offered a retort on CNN.

“You’re one of a hundred of the most powerful people in the country, and you’re acting like a 12-year-old in the schoolyard because you didn’t get your way,” O’Brien said of Mullin.

Tuesday’s kerfuffle was the second time in recent months that Mullin had challenged O’Brien to a fight.

“An attention-seeking union Teamster boss is trying to be punchy after our Senate hearing,” Mullin wrote in June on X.

“Okay, I accept your challenge. MMA fight for charity of our choice,” Mullin continued. “Sept 30th in Tulsa, Oklahoma. I’ll give you 3 days to accept.”

On his official Senate biograpy, Mullin describes himself as a former college wrestler who went on to compile a 5-0 record as a mixed martial arts fighter.

Senator Markwayne Mullin, far right, seen refreshing himself with a beverage in July. Chip Somodevilla/Getty

Material from prior Globe stories and from Globe wire services was used in this report.


Travis Andersen can be reached at