Republican Senate leader Mitch McConnell has labelled far-right Marjorie Taylor Greene’s embrace of conspiracy theories as “loony lies” and a “cancer” for their party.
Mr McConnell, the top Republican in the US Senate, has intensified pressure on the far-right Georgia congresswoman after, among other moves, she amplified QAnon conspiracy theorieswhich focus on the debunked belief that top Democrats are involved in child sex trafficking, Satan worship and cannibalism.
He told The Hill newspaper: “Somebody who’s suggested that perhaps no airplane hit the Pentagon on 9/11, that horrifying school shootings were pre-staged, and that the Clintons crashed JFK Jnr’s airplane is not living in reality.
“This has nothing to do with the challenges facing American families or the robust debates on substance that can strengthen our party.”
But Ms Greene would not be silenced by his stinging criticism.
In a strident broadside on Twitter, she suggested “the real cancer” for the Republican Party was “weak Republicans who only know how to lose gracefully”.
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“This is why we are losing our country,” she wrote.
Facebook videos surfaced last year showing Ms Greene had also expressed racist, antisemitic and anti-Muslim views.
Top Republicans denounced her at the time, hoping to block her from capturing the party’s nomination in her reliably red congressional district in northwest Georgia.
But after she won her primary, they were largely forced to accept her. Since then, even more of her past comments, postings and videos have been unearthed, though many were deleted recently after they came to light.
She “liked” Facebook posts that advocated violence against Democrats and the FBI. One suggested shooting House Speaker Nancy Pelosi in the head.
In response to a post raising the prospect of hanging former president Barack Obama, Greene responded that the “stage is being set”.
In an undated video posted online, Greene floated a conspiracy theory that wrongly suggested that the 2017 mass shooting that killed 58 people at a country music festival in Las Vegas could have been a staged operation to build support for gun control legislation.
Mr McConnell’s explicit condemnation adds to pressure on House Republicans to take action against Ms Greene even as she is claiming renewed support from former president Donald Trump.
On Monday, House of Representatives Democrats moved to strip her of her committee assignments – if Republican Leader Kevin McCarthy refused to do so himself.
Until now, Republican leaders in the House have been reluctant to criticise Trump supporters, like Ms Greene, out of concern that they could alienate the former president’s most ardent voters, underscoring a bitter divide over how the out-of-power party should navigate the two years until the next congressional elections.
Ms Greene’s views were in the spotlight even before she joined the House last month.
She once “liked” a Facebook post that challenged the veracity of the 2012 mass shooting at Sandy Hook Elementary School in Connecticut.
After her election, she seized on former president Trump’s false claims that the election was stolen and cheered on his supporters the day before the Capitol was stormed.
“It’s our 1776 moment!” she posted on the conservative-friendly social media platform Parler.
Last week, Mrs Pelosi pressed House Republicans to take action.
She asked: “Assigning her to the education committee, when she has mocked the killing of little children – what could they be thinking, or is thinking too generous a word for what they might be doing?
“It’s absolutely appalling.”