A Republican senator challenged a union boss to a cage fight after the latter’s ‘anyplace, anytime’ dare on social media.

Oklahoma GOP Sen. Markwayne Mullin threw down the gauntlet against International Brotherhood of Teamsters General President Sean O’Brien after the Teamsters boss went after him on social media.

Mullin told Fox News Digital that he accepted O’Brien’s challenge and that it’s ‘simple: he said ‘anyplace, anytime,’ so we accepted September 30th in Tulsa, Oklahoma.’

‘Too often, these big bully union bosses try to intimidate individuals and never get called out on it,’ Mullin said. ‘I refuse to tolerate loudmouth bullies like O’Brien who got suspended over threats to his own union members, thinks unions ought to be ‘militant organizations’ and vilifies right-to-work states like Oklahoma – all while calling for fights on social media.’

The comments came after O’Brien took shots at Mullin on social media.

‘Greedy CEO who pretends like he’s self made. In reality, just a clown [and] fraud,’ O’Brien wrote on Twitter. ‘Quit the tough guy act in these senate (sic) hearings.’

‘You know where to find me,’ he continued. ‘Anyplace, Anytime cowboy.’

Mullin responded on Twitter on Monday, challenging O’Brien to a charitable mixed martial arts (MMA) fight at the end of September in Oklahoma.

‘An attention-seeking union Teamster boss is trying to be punchy after our Senate hearing,’ the former MMA fighter wrote. ‘Okay, I accept your challenge. MMA fight for charity of our choice. Sept 30th in Tulsa, Oklahoma.’

‘I’ll give you 3 days to accept,’ Mullin added.

O’Brien did not immediately respond to Fox News Digital’s request for comment.

Mullin and O’Brien have traded barbs both online and offline, with the two previously getting into it over the Teamsters president’s salary compared to those of his union members during a Senate Health, Education, Labor and Pensions Committee hearing in March.

The minutes-long confrontation began with Mullin, who owns and operates a plumbing business, declaring he was ‘not against unions’ but also pointing to the intimidation he said he and his employees received from unions when they started being awarded jobs that typically went to union workers.

‘They would show up at my house. They’d be leaning up against my trucks. I’m not afraid of a physical confrontation, in fact sometimes I look forward to it. That’s not my problem. But when you’re doing that to my employees?’ Mullin said.

‘For what? Because we were paying higher wages? Because we had better benefits, and [weren’t] requiring them to pay your guys’ exorbitant salaries?’ he added before asking O’Brien what he made as a salary.

O’Brien began to answer, but Mullin continued, saying O’Brien made $193,000 in 2019 while the average driver makes $35,000 a year. ‘And what do you bring to the table?’ he asked O’Brien.

‘That’s inaccurate. State facts. That’s inaccurate,’ O’Brien responded as the two began to talk over each other.

Mullin repeated his statistic on salaries and said, ‘If you don’t know your facts, then maybe you shouldn’t be in your position.’ He then restated his earlier question to O’Brien, asking what he brought to the table for his large salary.

‘What job have you created – one job – other than sucking the paycheck out of somebody else?’ he asked.

‘You’re out of line, man,’ O’Brien responded as committee Chair Sen. Bernie Sanders, I-Vt., attempted to stop the back-and-forth and provide space for O’Brien to respond to Mullin.

The two ignored Sanders and continued talking over each other, appearing to grow increasingly frustrated, before Mullin said, ‘Sir, you need to shut your mouth because you don’t know what you’re talking about.’

‘You’re going to tell me to shut my mouth?’ O’Brien responded before mocking Mullin’s opening statement in which he said he wasn’t ‘afraid’ of a physical altercation.

Sanders eventually quieted the two and made Mullin provide O’Brien time to speak.

Fox News Digital’s Brandon Gillespie contributed reporting.