Democrats in the US House of Representatives will force a vote on the fate of a newly-elected Republican congresswoman over incendiary rhetoric.
Marjorie Taylor Greene has promoted unfounded conspiracy theories and shown support for violence against Democrats.
House Republican leader Kevin McCarthy condemned the remarks, but refused to punish Ms Greene, saying the remarks were made before she was elected.
The vote is set to take place on Thursday afternoon.
Democrats, who control the chamber, say they will vote to expel her from the education and budget committees.
Most legislation goes through a committee before reaching the House floor. Committee positions can determine the sway of individual lawmakers in their party.
Who is Marjorie Taylor Greene?
She was elected in November, representing a district in the southern state of Georgia. She is widely known for expressing support for QAnon, a bizarre conspiracy theory that former President Donald Trump was waging a clandestine war on a cabal of child-abusers.
Before taking office, she liked posts calling for violence against Democratic lawmakers, claimed that school shootings and the 9/11 terror attack were staged events, and suggested Muslims should not serve in government, among other comments online.
Her harangue of a teenage survivor of a school shooting in Parkland, Florida, was recently unearthed.
Last month, Mrs Greene introduced a measure attempting to impeach US President Joe Biden, accusing him of corruption and abuse of power, which made her a heroine of the party's pro-Trump wing.
Top Republican lawmakers have been outspoken in their criticism of Mrs Greene's past comments.
Senator Marco Rubio of Florida called her "either deranged or a sadist". Senate Republican leader Mitch McConnell of Kentucky said she had embraced "loony lies" that were a "cancer" to the party. Senator Todd Young of Indiana called her "nutty" and "an embarrassment".
What did Kevin McCarthy say?
Mr McCarthy, a California representative, said Mrs Greene's comments had caused "deep wounds to many".
"Past comments from and endorsed by Marjorie Taylor Greene on school shootings, political violence and anti-Semitic conspiracy theories do not represent the values or beliefs of the House Republican Conference," he said in a statement on Wednesday.
"I condemn those comments unequivocally. I condemned them in the past and continue to condemn them today."
He added: "I made this clear to Marjorie when we met [on Tuesday]. I also made clear that as a member of Congress we have a responsibility to hold ourselves to a higher standard than how she presented herself as a private citizen."
But Mr McCarthy accused Democrats of a double standard and of failing to hold their own lawmakers to account.
The Republican party has previously stripped lawmakers of committee assignments. In January 2019, Steve King of Iowa was expelled from three panels after he questioned why white supremacy is considered offensive.
How has Marjorie Taylor Greene responded?
According to the Hill, a political news outlet, Mrs Greene received a standing ovation at a closed-doors meeting with members of her party on Wednesday after she apologised for her past remarks.
She reportedly told fellow Republicans that she had erred in being curious about QAnon.
She also told her children that she had learned a lesson about sharing posts on social media, two sources in the room told the Hill.
Mrs Greene meanwhile said on Twitter on Wednesday that she had raised $160,000 over just the last two days for her political campaigning, adding: "Let's keep sending the message to the Democrat mob."
Conflicting currents within the Republican Party
The House of Representatives is heading toward a showdown on Thursday over the fate of Marjorie Taylor Greene, the freshman congresswoman with a penchant for trafficking in bizarre right-wing conspiracy theories.
Every attempt at reaching some sort of resolution to avoid a floor vote by the whole chamber - an apology by Mrs Greene, sanctions imposed by the Republican leadership or some compromise acceptable to Democrats - has been in vain.
The stand-off reflects the conflicting currents within the Republican Party. Some, like Senate minority leader Mitch McConnell, view Mrs Greene as a symptom of the corrosive effects of Donald Trump's politics. A clear renunciation, then, would be a welcome step away from the ex-president.
Others consider the move to punish Mrs Greene only the latest attempt to persecute and silence an outspoken conservative voice.
Democrats, sensing an advantage, are pushing for a very public confrontation, even if some are uneasy about the precedent it might set.
Meanwhile, Mrs Greene continues to raise her profile - as a hero to some on the right and, perhaps, a martyr.
What will Democrats do now?
House Speaker Nancy Pelosi, the chamber's most powerful Democrat, said they would proceed with a vote on Thursday to expel Mrs Greene from the education and budget committees.
The measure requires a simple majority to pass.
The California congresswoman said in a statement: "McCarthy's failure to lead his party effectively hands the keys over to Greene - an anti-Semite, QAnon adherent and 9/11 Truther."
Republicans are seeking to retaliate by trying to have a Democratic lawmaker, Ilhan Omar, expelled from her committees over an anti-Semitism furore.
In February 2019, the Minnesota congresswoman suggested US lawmakers only support Israel because of lobby money. She apologised, and no action was taken against her. House Democrats voted to condemn anti-Semitism, though their resolution did not name Ms Omar.
On Wednesday, the Somali-born Muslim issued a statement accusing Republicans of a "desperate smear rooted in racism, misogyny, and Islamophobia" to try to "distract" from the Greene controversy.
Liz Cheney survives secret ballot
On Wednesday night, Liz Cheney, the third-highest ranking Republican, survived a vote to oust her from her leadership position after she enraged Trump supporters by joining 10 Republicans in breaking ranks last month to impeach the former president.
She rode out the secret ballot by 145-61.
"I won't apologise for the [impeachment] vote," the Wyoming lawmaker, who is a daughter of former Vice-President Dick Cheney, told the closed-doors House Republican meeting earlier in the evening.
During a pause in that private meeting, Mr McCarthy told reporters he had defended Ms Cheney.
"People can have differences of opinion," he said. "That's what you can have a discussion about. Liz has a right to vote her conscience."