The armed attack this week on an F.B.I. office in Ohio by a supporter of former President Donald J. Trump who was enraged by the bureau’s search of Mr. Trump’s private residence in Florida was one of the most disturbing episodes of right-wing political violence in recent months.
But it was hardly the only one.
In the year and a half since a pro-Trump mob stormed the Capitol, threats of political violence and actual attacks have become a steady reality of American life, affecting school board officials, election workers, flight attendants, librarians and even members of Congress, often with few headlines and little reaction from politicians.
In late June, a former Marine stepped down as the grand marshal of a July 4 parade in Houston after a deluge of threats that focused on her support of transgender rights. A few weeks later, the gay mayor of an Oklahoma city quit his job after what he described as a series of “threats and attacks bordering on violence.”
Even the federal judge who authorized the warrant to search for classified material at Mar-a-Lago, Mr. Trump’s beachfront home and club, became a target. On pro-Trump message boards, several threats were issued against him and his family, with one person writing, “I see a rope around his neck.”
While this welter of events may feel disparate, occurring at different times and places and to different types of people, scholars who study political violence point to a common thread: the heightened use of bellicose, dehumanizing and apocalyptic language, particularly by prominent figures in right-wing politics and media.
Several right-wing or Republican figures reacted to the search of Mar-a-Lago not only with demands to dismantle the F.B.I., but also with warnings that the action had triggered “war.”
“This just shows everyone what many of us have been saying for a very long time,” Joe Kent, a Trump-endorsed House candidate in Washington State, said on a podcast run by Stephen K. Bannon, Mr. Trump’s former chief political strategist. “We’re at war.”
On Thursday, a 42-year-old Ohio man, identified as Ricky W. Shiffer, showed up at the Cincinnati field office of the F.B.I. with an AR-15-style rifle and was subsequently shot to death after firing multiple times at the police during a standoff. There is no evidence of what prompted Mr. Shiffer to act. But Mr. Shiffer’s social media posts later revealed that he was full of rage about, among other things, the search at Mar-a-Lago — and that he wanted revenge.
“Violence is not (all) terrorism,” he wrote — on Mr. Trump’s own social media app, Truth Social. “Kill the F.B.I. on sight.”
Despite that threat, one day later, when the right-wing media outlet Breitbart News published the warrant underlying the Mar-a-Lago search, it did not redact the names of the F.B.I. agents on the document. Almost immediately afterward, posts on a pro-Trump chat board referred to them as “traitors.”
According to the F.B.I., there are now about 2,700 open domestic terrorism investigations — a number that has doubled since the spring of 2020 — and that does not include lesser but still serious incidents that do not rise to the level of federal inquiry. Last year, threats against members of Congress reached a record high of 9,600, according to data provided by the Capitol Police.
Nonetheless, it is exceptionally rare for most adults to willfully inflict harm on other people, especially for political reasons, said Rachel Kleinfeld, a senior fellow in the democracy, conflict and governance program at the Carnegie Endowment for International Peace.
Still, Ms. Kleinfeld said, there are ways of lowering the average person’s tolerance for violence.
If political aggression is set in the context of a war, she suggested, ordinary people with no prior history of violence are more likely to accept it. Political violence can also be made more palatable by couching it as defensive action against a belligerent enemy. That is particularly true if an adversary is persistently described as irredeemably evil or less than human.
“The right, at this point, is doing all three of these things at once,” Ms. Kleinfeld said.
There is little evidence that Republicans and right-wing media figures have tempered their rhetoric, even as Congress and the Justice Department investigate the Jan. 6 attack. Several defendants charged in the riot have said they were moved to act by Mr. Trump’s words. Still, many Republicans have sought to minimize his role.
Even before the search at Mar-a-Lago this week, some of Mr. Trump’s most vocal supporters had been casting the political stakes as existential, suggesting that the country was already embroiled in an end-of-times clash between irreconcilable foes.
“This is truly a battle between those who want to save America and those who want to destroy her,” Kari Lake, the Republican nominee for the governor of Arizona, told the crowd at the Conservative Political Action Conference in Dallas in early August. “That’s where we are at the moment. My question to you is: Are you in this fight with us?”
After the search of Mr. Trump’s residence, Ms. Lake declared: “Our government is rotten to the core. These tyrants will stop at nothing to silence the patriots who are working hard to save America.”
“If we accept it,” she added, “America is dead.”
Ms. Lake’s campaign spokesman, Ross Trumble, said that any suggestion that her rhetoric created conditions that could lead to violence was a “tired game of dishonestly blaming Republicans.”
But the use of violence and violent language is not solely a problem on the right.
Some recent studies have found that a roughly equal percentage of liberals and conservatives agree that violence against the government is either “definitely” or “probably” justifiable. Others have shown that while support for political violence has doubled among Republicans since Mr. Trump took office, it has also increased — albeit more slowly — among Democrats.
There have also been some high-profile recent criminal cases involving political violence by left-leaning defendants, including one filed against a California man who was charged with attempted murder for showing up armed with a pistol, a knife and other weapons near the Maryland home of Justice Brett M. Kavanaugh in June.
Republicans have often criticized Democrats for paying scant attention to the Kavanaugh incident, and for only caring about aggression when it comes from the right. Some have pointed to a string of episodes — not all related to political violence — that reach back to 2017.
“Dangerous rhetoric from the left led to an assassination attempt on a U.S. Supreme Court Justice, a shooting at a congressional baseball practice, Molotov cocktails at pregnancy centers, rampant crime in major cities and an open border. Call out the left on their threatening hyperbole, then we will talk,” said Emma Vaughn, a Republican National Committee spokeswoman.
Still, the F.B.I. has repeatedly said that extremist violence from right-wing actors is one of the biggest threats confronting the bureau. Moreover, many Republican office seekers have directly incorporated violent language and imagery into their campaigns, including Eric Greitens, who ran an advertisement in his Missouri Senate race showing himself racking a shotgun, accompanied by men armed with assault rifles as they stormed — SWAT team-style — into a home in search of “RINOs,” or “Republicans in name only.”
The party’s more established leaders have often used a different tactic, casting longstanding policy disputes over abortion, gun rights and immigration as more than the usual political tussling by depicting them as dire conflicts, with the future of the republic hanging in the balance.
“Anger is a really productive emotion for politics,” said Lilliana Mason, an associate professor of political science at Johns Hopkins University. “It helps motivate people to participate in democracy by doing things like putting signs in their yard, vote, or get others to vote, but can easily spill over into violence.”
Ms. Mason added: “It’s a powerful electoral tool that can be easily misused.”
After the F.B.I. descended on Mar-a-Lago on Aug. 8, one of the most common Republican responses was an effort to stoke fears by suggesting that if federal agents could enter the private domain of a former president, then no one on the right could possibly be safe.
“Trump Targeted by Biden Administration, and They Can Do It to You, Too,” read the headline of an opinion article by Ronna McDaniel, the chairwoman of the Republican National Committee, that was published on the Fox News website two days after the search took place.
After condemning the F.B.I. for using “third-world tactics” — despite the fact the search had been authorized by a court-approved warrant — Ms. McDaniel listed a litany of purported actions taken by Democrats, each of them suggesting the party was out to get ordinary Republicans.
Last October, Ms. McDaniel wrote, the Justice Department “labeled parents concerned about their kids’ educations as ‘domestic terrorists.’” (In fact, the F.B.I., including its counterterrorism section, began tracking threats against school administrators, teachers and board members to assess the extent of the problem.)
Representative Lauren Boebert, Republican of Colorado, put it more bluntly.
“They hate us,” Ms. Boebert wrote in a tweet on Aug. 11. “They don’t just want to eliminate conservative ideology. They want to eliminate conservatives.”
Experts note that rhetoric does not have to directly reference violence to contribute to threats. Dehumanizing language also plays a role.
They point to efforts to label immigrants as invaders and people who support teaching about transgender and gay rights as “groomers.” That term, which connotes the sexual indoctrination of underage children, is a reference to the QAnon conspiracy theory, which baselessly holds that Democrats and other liberals are Satan-worshipping pedophiles who traffic children.
Mr. Shiffer’s social media posts suggest that he opposed the movement for transgender rights. In one of the posts, he said he was prepared for “war against the communists who chemically neuter prepubescent children and call it gender transitioning.”
Adam Graham, who was one of fewer than half a dozen L.G.B.T. elected officials in Oklahoma, said that repeated threats forced him to resign.
His tires were slashed, he said. He was harassed by residents at a council meeting, called a homophobic epithet and followed near his home.
“Being followed while walking your dog,” Mr. Graham said. “That’s very scary. I was afraid what would they do next if I don’t step down.”
Robert Pape, a professor at the University of Chicago who studies political violence, has conducted half a dozen nationwide polls since the Jan. 6 attack and has repeatedly found the same results: that between 15 million and 20 million American adults believe that violence would be justified to return Mr. Trump to office.
This kind of “community support,” Mr. Pape said, can normalize violence.
“Community support lowers the threshold at which volatile people will take action,” Mr. Pape said, “because he or she will tell themselves that people in the community actually support them. Maybe it’s only 10 percent of the community, but that’s still a large group.”
Mr. Pape and other violence researchers often compare conditions in the United States to those of dry forest with lots of combustible material on the ground. All it takes is a spark, like the search of Mar-a-Lago, to ignite the tinder.
With Mr. Trump facing multiple investigations even as he considers yet another run for office, there are many possible sparks that could flare up in the days and weeks ahead.
“We’re in wildfire season,” Mr. Pape said, “and will be for quite some time.”
Reporting was contributed by Neil Vigdor, Frances Robles, Mark Walker and Alyce McFadden.