A Republican criticized for promoting racist videos and adamantly supporting the far-right QAnon conspiracy theory faces a neurosurgeon who campaigned on his experience to improve the health care system in Tuesday's GOP primary runoff for an open U.S. House seat representing northwest Georgia.

The results could indicate just how far candidates can push the limits of political rhetoric in the age of President Donald Trump before triggering a backlash from voters.

Businesswoman Marjorie Taylor Greene and Dr. John Cowan have both positioned themselves as staunch Trump supporters, pushing anti-abortion, pro-gun and pro-border wall messages. But while Cowan has taken a more traditional campaign approach, Greene has found a loyal following — and controversy — by sharing video chats and social posts expressing racist, Islamophobic and anti-Semitic views.

Republican congressional candidate John Cowan greets supporters Tueaday, June 9, 2020 in Rome, Georgia at an election night party. Cowan is in an Aug. 11 runoff for the Republican nomination in northwest Georgia's 14th Congressional District against Marjorie Taylor Greene, who has come under fire for remarks she made in videos she recorded. (Jeremy StewartRome News-Tribune via AP)

Republican congressional candidate John Cowan greets supporters Tueaday, June 9, 2020 in Rome, Georgia at an election night party. Cowan is in an Aug. 11 runoff for the Republican nomination in northwest Georgia's 14th Congressional District against Marjorie Taylor Greene, who has come under fire for remarks she made in videos she recorded. (Jeremy StewartRome News-Tribune via AP)

Some Republican officials have condemned her campaign, raising Cowan’s profile. But her stalwarts were outside election sites on Tuesday.

At the Shelton Elementary School polling site in Paulding County, a large Marjorie Greene campaign sign declared her motto in all capital letters: “SAVE AMERICA, STOP SOCIALISM!”

Pamela Reardon, who wore a pin featuring Trump and the American flag, said she supports Greene because she connects with people and she is anti-abortion, a defender of the Second Amendment and “a true Christian.”

Reardon said she's heard the critics of Greene’s social media posts, but claimed Greene "never said anything racist like they say she has.”

“I got behind her because of her honesty,” she said. “She’s not going to be bought by anybody. I could tell that her heart was pure.”

At East Paulding Middle School near Dallas, Georgia, Natalie Higgins sat on a lawn chair in a steady rain outside the polling place with a polka-dot umbrella and red and white campaign signs for a state Senate candidate who is a family friend.

Higgins, who is from nearby Hiram, said she voted for Cowan because he supports law enforcement and because “he just seemed to run a cleaner campaign."

Polls in Floyd County, one of the more populous counties in the 14th Congressional District, will remain open two hours late until 9 p.m. after a judge ordered the extension because “software issues” hampered voting there early Tuesday.

Lines were light elsewhere in the district. Three polling sites in Paulding County had no lines Tuesday morning and voters were able to walk right in and cast a ballot.

The runoff comes two months after a confluence of issues, including problems with the state’s new touchscreen voting machines, coronavirus precautions and a reduced workforce, disrupted statewide primaries in June. That caused hours-long lines in some place, particularly in Atlanta’s Fulton County, which is outside the district.

Greene led in the initial June 9 Republican primary by a wide margin but failed to secure enough votes to win the nomination outright.

Soon after that race, a series of videos were unearthed in which Greene complains of an “Islamic invasion” into government offices, claims Black and Hispanic men are held back by “gangs and dealing drugs,” and pushes an anti-Semitic conspiracy theory that billionaire philanthropist George Soros, who is Jewish, collaborated with the Nazis.

Greene also is part of a growing list of candidates who have expressed support for QAnon, a U.S. conspiracy theory popular among some Trump supporters. Lauren Boebert, another candidate who has expressed support for QAnon, recently upset a five-term congressman in a Republican primary in Colorado.

She has responded to criticism of her rhetoric by blasting “the fake news media” and “the DC swamp.”

Cowan has strongly pushed back on Greene’s comments, saying in a recent interview that she “deserves her own YouTube channel, and not a seat in Congress.”

He says he’d use his experience as a doctor to improve the health care system and he'd push to repeal the Affordable Care Act, though he supports keeping protections for preexisting conditions.

Greene has in turn attacked Cowan as not being sufficiently conservative, branding him a RINO, a derisive acronym that stands for Republican In Name Only.

The district stretches from the outskirts of metro Atlanta to the largely rural northwest corner of the state.

The winner of Tuesday’s runoff will face Democrat Kevin Van Ausdal in November. Republican Rep. Tom Graves, who did not seek reelection, last won the seat with over 76% of the vote in 2018.

Associated Press writer Jeff Martin in Dallas, Georgia, contributed to this report.