The Democratic-led US House voted Thursday to discipline a congresswoman who embraced QAnon conspiracy theories and endorsed violence, capping weeks of mounting turmoil over holding to account a lawmaker whose extremist rhetoric caused a rupture in Republican ranks.

Conservative first-term congresswoman Marjorie Taylor Greene, facing bipartisan opprobrium for a series of disturbing comments and support of social media posts advocating the assassination of Democratic lawmakers, was stripped of her two assignments on the House education and budget committees.

The punishment was meted out in a modestly bipartisan vote of 230 to 199 which occurred hours after Greene, a fierce supporter of former president Donald Trump, took to the House floor to renounce the conspiracy movement and expressed regret for spreading misinformation.

Eleven Republicans defied their party to join all voting Democrats in disciplining Greene, whose alarming actions before she ran for office included posting video of herself harassing a teen school shooting survivor and casting doubt on the September 11, 2001 attacks.

"No member ought to be permitted to engage in the kind of behavior that Representative Greene has and face zero consequences," number two House Democrat Steny Hoyer told the chamber.

"This vote can be a first step in correcting the error of those who so far have chosen to do nothing."

But Republicans blasted the action against one of their own as shattering congressional precedent, with members of leadership warning of potential political payback should they regain power.

US Representative Marjorie Taylor Greene, accused by Democrats and some Republicans of extremist and dangerous rhetoric, faced a disciplinary House floor vote to strip her of committee assignments
US Representative Marjorie Taylor Greene, accused by Democrats and some Republicans of extremist and dangerous rhetoric, faced a disciplinary House floor vote to strip her of committee assignments AFP / Nicholas Kamm

Number three Republican Liz Cheney, fresh from surviving a challenge to her leadership after she voted to impeach Trump last month, said that while Greene's comments were reprehensible, Democrats "have no business determining which Republicans sit on committees."

"This vote today sets a dangerous precedent for this institution that Democrats may regret when Republicans regain the majority."

Greene, 46, had taken to the House floor to plead her case before the vote.

"These were words of the past, and these things... do not represent my values," she said.

"I was allowed to believe things that weren't true and I would ask questions about them and talk about them," she added. "And that is absolutely what I regret."

In a striking moment on the House floor, Greene acknowledged that "school shootings are absolutely real" and that "9/11 absolutely happened" -- US tragedies that she has cast doubt on in the past.

But she did not directly apologize in her 10-minute speech, and Democrats swatted aside her posture of contrition.

US House Minority Leader Kevin McCarthy, at right, is struggling to unify a Republican Party splintered between loyalists to former president Donald Trump, and traditional conservatives and moderates uncomfortable with extremist rhetoric
US House Minority Leader Kevin McCarthy, at right, is struggling to unify a Republican Party splintered between loyalists to former president Donald Trump, and traditional conservatives and moderates uncomfortable with extremist rhetoric POOL / MICHAEL REYNOLDS

The vote came after the chamber's top Republican Kevin McCarthy balked at punishing her over her rhetoric, with the furor over Greene exposing deep party divisions in the wake of Trump's presidency.

Republicans were forced to go on record over Greene's conduct, which includes her trafficking in anti-Semitic, racist and Islamophobic tropes.

It was a closely watched moment, as the party attempts the balancing act of accommodating base supporters of the still-influential Trump, and winning back traditional Republicans who have bristled at Greene's unrestrained politics.

Republicans huddled in a closed-door session late Wednesday to debate the path forward. Dozens of members reportedly gave Greene a standing ovation when she addressed her colleagues.

But in the same meeting Cheney was given a vote of confidence, overcoming fierce backlash about her impeachment vote.

Greene and Cheney have become opposites of sorts in a tug-of-war over the GOP's direction post Trump.

Before running for Congress, Greene "liked" Facebook posts that advocated the execution of Democrats including House Speaker Nancy Pelosi.

In 2018 she asserted that California wildfires were ignited by a space laser controlled by a Jewish family, and she supported QAnon conspiracy theories that a "deep state" cabal operated against Trump when he was president.

"When I started finding misinformation, lies, things that were not true in these QAnon posts, I stopped believing it," Greene told the House.

But Hoyer wasn't buying it. The veteran Democrat turned to Republicans and showed them a placard of a Greene social media post that showed her brandishing a rifle next to images of three liberal House colleagues.

"None of us should take any pleasure in what we must do today," he said just before the vote.

"But to do nothing would be an abdication of our moral responsibility to our colleagues, to the House, to our values, to the truth, and to our country."