Conspiracy theorists won a major victory on Tuesday as Marjorie Taylor Greene, a Republican supporter of the convoluted pro-Trump movement QAnon, triumphed in her House primary runoff election in Georgia, all but ensuring that she will represent a deep-red district in Congress.
The ascension of Ms. Greene, who embraces a conspiracy theory that the F.B.I. has labeled a potential domestic terrorism threat, is likely to unsettle mainstream Republicans, who have sought to publicly distance themselves from QAnon supporters running for congressional office this cycle even as they quietly support some of them.
Ms. Greene defeated John Cowan, a neurosurgeon who is no less conservative or pro-Trump, in Georgia’s 14th Congressional District, one of the most Republican in the country. As of Wednesday morning, she led by 14 percentage points.
QAnon, a conspiracy theory that has attracted a fervent following since it emerged from the troll-infested fringes of the internet nearly three years ago, has already inspired real-world violence, including the killing of a mob boss. Its supporters are slowly becoming a political force that some Republicans feel they cannot afford to alienate, even as the party struggles to distance itself from racist and anti-Semitic conspiracy theories.
More than a dozen candidates who have expressed some degree of support for QAnon have run this year for Congress as Republicans, their path cleared by Mr. Trump’s own espousal of conspiracy theories.
Most are going to lose. But a few, Ms. Greene foremost among them, have managed to win primaries against Republicans whose only real ideological difference was that they don’t believe in QAnon.