Washington (AFP) – The shocking assault of top Democrat Nancy Pelosi's husband at their home has heightened concerns that unconstrained disinformation and toxic political partisanship could spill over into violence around next week's US midterm elections.

US security officials say unconstrained disinformation and political vitriol is volatile fuel for attacks, like the one in which a follower of right-wing conspiracy theories apparently sought to kidnap Nancy Pelosi over alleged election “lies.”

David DePape, who allegedly assaulted Pelosi's 82-year-old husband Paul in their San Francisco home when he found she wasn't there, posted conservative conspiracy theories on his website on election fraud, Covid vaccines, climate change, the Holocaust and trans people in schools.

The attack came one week before midterm congressional elections, as politicians and poll workers have reported a surge in threat messages and intimidation.

Those include, in Arizona, armed men patrolling ballot drop boxes, alarming people attempting to vote.

On Friday, the day of the Pelosi attack, US security agencies issued a warning that domestic violent extremists (DVE) pose “heightened threats” around the November 8 vote.

“Election-related perceptions of fraud and DVE reactions to divisive topics will likely drive sporadic DVE plotting of violence and broader efforts to justify violence in the lead up to and following the 2022 midterm election cycle,” the agencies said in a joint intelligence bulletin.

Trump rhetoric

Talk of political violence climbed after former president Donald Trump refused in November 2020 to accept his election defeat by Joe Biden, leading to the assault on the US Capitol by Trump supporters two months later, on January 6, 2021.

Since then the political rhetoric has not dampened, in part because Trump himself still dominates the Republican Party and tells supporters that Biden's Democrats are bent on stealing the upcoming elections.

In Robstown, Texas last week, Trump urged voters not to trust the polls, called Pelosi “crazy” and said “Biden and the far left lunatics are waging war on Texas,” among other accusations made without evidence.

“Biden and his left wing handlers are turning America into a police state,” he asserted, repeating his unfounded claim that “January 6th was caused because of a crooked stolen election.”

Democratic, Republican officials targeted

Nothing like January 6 has recurred. But there are enough incidents and social media-fuelled disinformation to give officials cause for worry.

In June an armed man traveled to Supreme Court Justice Brett Kavanaugh's home just outside Washington, unhappy about the high court's opposition to abortion rights. 

In July a man with a gun threatened Democratic Representative Pramila Jayapal at her home in Seattle. 

The same month a military veteran, later described as suffering from alcoholism and PTSD, tried to knife Republican New York governor candidate Lee Zeldin. 

And Democratic Congressman Eric Swalwell has been the target of numerous violent threats.

Swalwell placed the blame directly on Trump's fiery “Make American Great Again” movement.

“MAGA political violence is at peak level in America and it's going to get someone killed,” he wrote in August, urging Republican leaders to denounce it.

 Rampant disinformation

In addition, poll workers have reported widespread threats after Trump and his followers blamed them for his 2020 election loss.

Some areas say they now cannot recruit enough poll workers.

In Arizona — where tensions over the allegedly “stolen” 2020 presidential election have been particularly high —  armed people wielding video cameras have shown up at ballot drop boxes.

Such actions “raise serious concerns of voter intimidation,” the Justice Department said in a filing to the Arizona federal district court, where a lawsuit has been filed over the issue.

Underpinning the worries of violence is an atmosphere of copious disinformation online that angers readers and can lead them to launch attacks, as with Pelosi's attacker.

On Sunday the US government's top cybersecurity official Jen Easterly said there was “a very complex threat environment helped by “rampant disinformation” and “threats of harassment, intimidation and violence against election officials, polling places and voters.”

Disinformation “can undermine confidence in election integrity and that can be used to incite violence,” Easterly said on CBS.