A Republican senator and a union boss exchanged heated remarks in a Senate hearing this past March. Now — if there is any bite to the teamster's bark — there's a chance the two might exchange blows in the octagon.

What's the background?

During a Senate Health, Education, Labor and Pensions Committee hearing on March 8, Sen. Markwayne Mullin (R-Okla.) struck a nerve, intimating that while Sean O'Brien, general president of the International Brotherhood of Teamsters, makes close to $200,000 a year, he doesn't bring much "to the table."

Mullin asked the teamster boss, "What do you bring for that salary? ... What job have you created?"

O'Brien suggested the senator was "out of line," then proceeded to call him a "greedy CEO" and accused him of hiding money while running his plumbing company.

Despite sporadic efforts on the part of Sen. Bernie Sanders (I-Vt.) to intervene, Mullin hit back at O'Brien, saying, "You think you're smart? You think you're funny? You're not," intimating that the committee witness' combative testimony hinted at the kind of intimidation honest union workers routinely suffer at the hands of teamsters.

Markwayne Mullin Goes Nuclear On Labor Leader In Fiery Hearing On Unions youtu.be

Title fight

After stewing for months, O'Brien took to Twitter on June 21 to accuse Mullin of being "full of sh**," adding, "The more you run your mouth, the more you show the American public what a moron you are."

O'Brien proceeded to repeat his March comments, calling the Oklahoma senator a "Greedy CEO who pretends like he's self made" and a "clown."

The teamster boss went so far as to suggest his openness to fisticuffs, tweeting, "You know where to find me. Anyplace, Anytime cowboy."

Mullin, a Cherokee father of six and undefeated former MMA fighter, accepted the teamster's challenge, letting him know he had three days to agree to turn his typing hands into fists.

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

— (@)

A history of violence

According to Sherdog.com, Mullin won all three of his professional MMA fights in the middleweight class, despite a shoulder injured in his youth.

In November 2006, he won an Xtreme Fighting League bout against Bobby Kelley by submission with a rear-naked choke in 46 seconds.

In February 2007, he took out Clinton Bonds in an XFL SuperBrawl match by submission. He faced Bonds again in April 2007 and defeated him in 1:27 with a total knockout, ensured with punches.

The National Wrestling Hall of Fame indicated that "Mullin did whatever it took to wrestle through elementary and middle school, including switching schools four times after the school he was attending canceled its wrestling program."

In a well-timed Spectator profile released Monday, Ben Domenech suggested that the "veins on Mullin’s arms are the first thing you notice. He’s not built like a senator, he’s built like a man who could leap off the top rope and drive you into the mat. He is a member of the Cherokee Nation, the first Native American in the Senate since the retirement of Colorado’s Ben Nighthorse Campbell in 2005."

Domenech continued, "Ripped, bearded, with a belt buckle the size of a hubcap and a Stetson worn as if he’s had it on since the womb, he looks like Rip Wheeler from Yellowstone’s more ab-focused brother," adding, Mullin is the "most mercurial and unknown member of the Senate."

O'Brien has an opportunity to get to know the allegedly unknown senator a whole lot better.

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