The Capitol Police last year reported that they investigated more than double the number of threats against members of Congress as they did four years earlier. Driven by former President Donald Trump’s lies that the 2020 election was stolen from him, threats against election workers have exploded, with one in six reporting threats against them and many seasoned election administrators leaving the job or considering it.

“It’s definitely increased in the last five years,” said Jake Spano, mayor in the Minneapolis suburb of St. Louis Park and a board member of the National League of Cities, which issued a report in 2021 finding that 81 percent of local elected officials reported receiving threats and 87 percent saw the problem worsening.

Officials in Spano’s town got deluged in 2018, when Trump tweeted critically about its city council’s decision to stop saying the Pledge of Allegiance at the start of its meetings.

“The lasting impact of Donald Trump’s presidency is that he made it clear that the norms of how we treat each other no longer apply,” said Spano, a Democrat.

The threats are not simply an issue of coarsening of the national discourse. Experts warn they can be precursors of political violence.

In 2017, a man who belonged to a Facebook group called “Terminate the Republican Party” opened fire on GOP House members as they practiced for a charity baseball game, severely wounding now-House Majority Leader Steve Scalise. Last year, the 82-year-old husband of then-House Speaker Nancy Pelosi, a Democrat, was assaulted by a hammer-wielding man who had posted right-wing conspiracy theories online before breaking into the couple’s San Francisco home.

Also last year, a man was arrested with knives, a pistol and zip ties outside the home of Supreme Court Justice Brett Kavanaugh amid protests against the high court overturning women’s right to obtain abortions. Then an armed Ohio man in body armor who had been at the Jan. 6 attack on the Capitol was shot and killed after trying to enter an FBI office following that agency’s search last summer of Trump’s Florida resort, Mar-a-Lago.

Trump has repeatedly slammed the FBI and has called for a takeover of the Justice Department should he win the presidency again, as he faces additional charges related to his attempts to overturn the results of the 2020 election.

Trump has referred to the special counsel overseeing the federal prosecutions, Jack Smith, as “deranged” and an “out of touch lunatic,” and to the charges against him as “election interference and yet another attempt to rig and steal a presidential election.” He also has attacked a local Georgia prosecutor expected to file more charges against him next week, Fulton County District Attorney Fani Willis.

Experts warn the escalating rhetoric could increase the risks of violence, especially as the 2024 election and Trump’s trials draw closer. Lone attackers acting impulsively, rather than mass violence such as the Jan. 6 attack on the Capitol, are the greatest worry, said Javed Ali, a former senior FBI counterrorism official now at the University of Michigan.

“That threat can materialize very quickly with no notice,” he said.

In an affidavit from FBI agents, Craig Deleeuw Robertson sounded like he could be that type of threat.

Authorities said the self-employed woodworker referred to himself as a “MAGA Trumper” — referring to Trump’s ”Make America Great Again” slogan — and had posted threats against Manhattan District Attorney Alvin Bragg, U.S. Attorney General Merrick Garland and New York Attorney General Letitia James, all of whom have been targets of Trump’s own attacks on social media.

Trump’s Truth Social network was the first to warn the FBI about him after Robertson in March posted a threat to kill Bragg, the first prosecutor to file criminal charges against Trump.

Even after a visit from FBI agents, the affidavit said, Robertson continued posting violent words and imagery online, including quipping that if the FBI was still monitoring his posts he would “be sure to have a loaded gun in case you drop by again.” He also posted about killing Biden, who was due to visit the state Thursday.

Those who knew Robertson said he was not a danger to anyone, only an elderly, largely homebound conservative man spouting off online.

“He believed in his right to bear arms. He believed in his right to say what he feels. When it came down to it, he knew the Lord wouldn’t have approved of killing innocent people,” said Paul Searing, a local businessman who followed Robertson online for years and warned him when he crossed the line on social media. “Things got out of hand because he just was really frustrated.”

Michael German, a former FBI agent who is now a fellow with the Brennan Center for Justice, said social media can transform private venting into menacing-sounding threats.

“Things that may have been screamed at the television before now appear widely in public,” German said.

He said the problem is that federal law enforcement has been slow to go after organized right-wing violence, such as violent acts committed by the Oath Keepers, Proud Boys and similar groups before the Jan. 6, 2021, assault on the Capitol.

While threats against public officials are a routine part of the country’s history, German said the rhetoric by Trump and some of his supporters presents a new danger.

“What concerns me is that authority figures — not just Trump, but many others in the Republican Party — have promoted violent groups and dismissed the violence they’ve committed,” he said, adding that it sends a signal to some people who are sympathetic to the groups’ views.

Kurt Braddock, a communications professor at American University in Washington, D.C., said rhetoric doesn’t have to explicitly direct supporters to commit violence. Even if it inspires just a tiny fraction to commit crimes, it can still be dangerous given the extraordinary reach of political and extremist messaging across the internet and the millions of people who absorb it.

“You get to the point where at least one person can interpret that as a call to violence,” Braddock said. “As we’ve seen, one person can do a lot of damage.”

Though the danger is greater and the rhetoric harsher on the political right, Braddock said, the left also has responsibility. Shortly before the arrest outside Kavanaugh’s house, Senate Majority Leader Chuck Schumer had warned that the GOP-appointed Supreme Court majority had “released the whirlwind” and “will pay the price” with its ruling overturning Roe v. Wade.

Still, experts warned against presuming that too many Americans are so radicalized that they might engage in politically motivated violence.

Joe Mernyk, a doctoral student in Stanford University’s Polarization and Social Change Lab, surveyed Democrats and Republicans about their support for political violence and found it to be very low. But perceptions of those in the other party provided a different picture: People in each party believed members of the other had high support for violence.

When participants were told that, in fact, support for violence was low on the other side, their own support for violence dropped even lower, Mernyk said,

Mernyk stressed the importance of “making sure people know these people, like the guy in Utah, are not representative of the Republican Party or the party’s attitudes.”