Redding, California - In this week's Super Tuesday primaries, security guards will monitor the back door at one Shasta County polling precinct – a sign of the high political tensions in rural northern California.

Two years ago, angry men burst into the precinct to contest the results of a local election, their anger fueled by conspiracy theories surrounding electronic vote-counting systems.

"This is an attack on the process... It's hard sometimes, and it's discouraging," says Joanna Francescut, assistant county clerk and registrar of voters.

This rural northern California area mirrors the forces fracturing America ever since Donald Trump falsely asserted that the 2020 election was stolen from him.

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In poll after poll, a majority of Republican voters across the country continue to regard Joe Biden as an illegitimate president.

In historically conservative Shasta County, Trump soundly defeated Biden, garnering 65 percent of the vote. But last year, newly elected Republicans sought to bar the use of Dominion Voting Systems machines, the focus of numerous debunked conspiracy theories.

Supporters of the Trumpist lie, the officials also invited conspiracy theorists from all over the country to expound their theories at public meetings.

Suspicions run deep among residents of Redding, the county seat. Many firmly believe in "computer manipulation" and describe the Dominion vote-counting machines as "black boxes" that can be manipulated in secret.

"Donald Trump won despite the cheating against him here in Shasta County," says Laura Hobbs, a stay-at-home mom.

Rulings by some 50 US courts that dismissed charges of electoral fraud carry no weight with such voters. Nor does the settlement last year in which Fox News agreed to pay Dominion $787.5 million over its airing of the false allegations, a move to avert a trial on defamation charges.

Faced with a backlash, election officials in Shasta County scrapped the Dominion machines, vowing to count all votes by hand. That set off a showdown with the Democratically controlled state legislature, which enacted a law that narrowly limits hand counting of ballots to races with fewer than 1,000 eligible registered voters.

Doubts about electoral processes are spreading throughout the United States: A rural county in Arizona also recently tried to ditch its voting machines.

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Francescut is dismayed by this defiance: her team already manually counts a small proportion of the ballots at each election to check that the machines are working correctly, in accordance with the law.

"It's key to do both," she tells AFP. "You can't rely just on machines. You can't rely just on hand count."

After the showdown, Shasta County authorities bought new machines produced by another company. Local Republicans are denouncing an "overreach" by the state legislature and are considering further recourse.

"The cheating is continuing, and it's putting a cloud over the March 5 primary," says County Supervisor Patrick Jones. "We are going to not stop until we have fair elections."

In Redding, many residents expect Trump to crush his rival, Nikki Haley, on Tuesday.

But local races unleash hotter passions than the national election. The central question is: will the anti-machine Trumpists hold onto power?

Jones, a gunsmith who wears a pistol strapped to his ankle at all times, already threatens to deny any outcome other than his team's re-election – just like Trump did after his 2020 election loss.

"I believe that cheating is occurring right now," Jones says. "If we determine that there has been fraud within our elections... I will not be able to certify any fraudulent results."

Rancher Mary Rickert has trouble recognizing the area where she's been raising cows for five decades.

At 71, she is one of the few Republican-elected county supervisors to oppose the project to abandon vote-counting machines – which has earned her the opprobrium of Trumpists.

"If they do not maintain their board positions... there's going to be a huge amount of turmoil," Rickert frets, noting that a local militia operates in the county, which issues a large number of gun permits. "We might even need the National Guard."

Rickert voted for Trump twice but swears she'll never do so again. A not insignificant sector of the Republican Party shares her views, and their actions may have a decisive impact on the November presidential election.

"We're going to be a very fractured party moving forward, and I don't think we're going to be very effective," she says.