‘Stand your butt up!’: GOP senator challenges witness to a brawl during hearing

Tensions boiled over at a United States Senate committee hearing after Republican Senator Markwayne Mullin threatened to fight Teamsters President Sean O’Brien.

The incident occurred during a Health, Education, Labor, and Pensions committee hearing on Tuesday, local time, chaired by independent Senator Bernie Sanders.

Senator Mullin threatened to engage in a physical altercation after a tweet where Mr O’Brien challenged him “any time” or “any place”.

Mr Mullin stood up, ready to confront the labor union boss, who responded in kind, leading to a heated exchange.

Chairman Sanders intervened, urging both to sit down and reminding them of their positions as senators.

Despite Mr Sanders’ attempts to steer the discussion, the pair continued to argue, disregarding his pleas.

The Vermont senator eventually took control of the situation before it could get out of hand.

Video footage of the altercation has since gone viral, prompting Fox News host Laura Ingraham to describe it as an “utter embarrassment”.