Sen. Markwayne Mullin is done with the snippy tweets. He wants a real tussle with the boss of the International Brotherhood of Teamsters.

Mullin (R-Okla.), who has an unbeaten mixed martial arts record to his credit, formally challenged Teamsters General President Sean O’Brien to a cage fight for charity on Monday.

“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,” Mullin told O’Brien on Twitter. “Sept 30th in Tulsa, Oklahoma. I’ll give you three days to accept.”

Mullin’s challenge followed O’Brien calling him a “Greedy CEO who pretends like he’s self made” last week.

“In reality, just a clown & fraud,” added O’Brien, tweeting under the provocative handle “TeamsterSOB”. “Always has been, always will be. Quit the tough guy act in these senate hearings. You know where to find me. Anyplace, Anytime cowboy.”

Both men have been trading barbs since March, when O’Brien dinged Mullin — who owns a plumbing company — during a testy Senate Health, Education, Labor and Pensions Committee hearing about unionization.

Mullin accused Teamsters of trying to intimidate his employees into unionizing and charged O’Brien was “sucking” money from worker paychecks by “forcing them to pay dues.”

After saying the senator was “out of line,” O’Brien said the Teamsters “create opportunity because we hold greedy CEOs like yourself accountable.”

“You calling me a greedy CEO?” Mullin asked.

“Oh yeah, you are,” O’Brien replied. “You want to attack my salary, I’ll attack yours …What did you make when you owned your company?”

“I kept my salary down at about $50,000 a year because I invested every penny into it,” Mullin said.

OK, all right,” said O’Brien, before restarting hostilities by asking Mullin: “You mean you hid money?

Mullin recalled that war of words last week, eliciting O’Brien’s ire.

“Hey, JohnWayne Mullin..First off, my name’s O’Brien not O’Malley. Secondly, you should get your facts straight because every time you speak in these hearings you’re full of sh*t,” O’Brien tweeted June 21. “The more you run your mouth, the more you show the American public what a moron you are.”

The Teamsters, which touts 1.2 million members, is among the largest labor unions on the planet and represents workers in the trucking, rail and publishing industries, among others.

Mullin previously said he would fight porn star Stormy Daniel’s disgraced former lawyer Michael Avenatti, but that never manifested. Avenatti is currently behind bars.

Mullin was elected to the House in 2012 and ascended to the Senate after winning a special election to succeed retiring Sen. Jim Inhofe (R-Okla.) last year.

Mullin and O’Brien aren’t the only major figures to stir chatter over a public scrap via Twitter.

Last week, Twitter CEO Elon Musk taunted fellow social media titan Mark Zuckerberg into a “cage fight.” Zuckerberg, a jiu-jitsu disciple, appeared to accept.

Musk, who was peeved by Facebook’s reported plans to produce a micro-blogging Twitter alternative, has teased that his signature move will be “the walrus,” a technique meant to immobilize his enemies by sitting on top of them and doing absolutely nothing.

Musk has admitted he has not done much training to compete with Zuckerberg, making the South African-born CEO a decided underdog.

A Teamsters rep did not immediately respond to a request for comment.