(The Hill) – Just hours after his arrest last month near the home of Justice Brett Kavanaugh, a 26-year-old California man carrying a Glock 17 pistol, burglary tools and zip ties told an FBI agent what had inspired his cross-country trip to assassinate the conservative Supreme Court justice. 

The suspect, who has pleaded not guilty and faces up to 20 years in prison if convicted, told a detective he was upset about the leaked draft opinion overturning Roe v. Wade and the school shooting in Uvalde, Texas, that killed two teachers and 19 children. According to court records, the suspect believed Kavanaugh would vote to further loosen gun laws, and said that killing the justice before turning the gun on himself would give his life purpose. 

The chilling incident is among a series of violent threats recently that have targeted political figures and comes amid a shifting landscape in which the share of partisans who think violence is sometimes justified to achieve political ends has grown significantly. 

“The idea that violence is legitimate for political purposes has moved into the mainstream,” said Robert Pape, a political science professor at the University of Chicago. “It’s still a minority. … But if you’ve got 10 percent or 15 percent of a community that believes that violence is acceptable for some political causes, that just encourages more violence for those causes.” 

A rash of recent violent threats against U.S. lawmakers has raised new concerns about the safety of political figures, particularly after the assassination of former Japanese Prime Minister Shinzo Abe illustrated in the starkest possible terms the stakes of a heightened threat environment. And the Jan. 6 coup attempt served to remind Americans that the U.S. is not immune from the kind of political violence that is relatively common in some parts of the world.

One recent high-profile incident came earlier this week when a man was arrested for allegedly threatening to kill Rep. Pramila Jayapal (D-Wash.), who leads the Congressional Progressive Caucus. According to law enforcement, officers discovered the suspect in the street outside Jayapal’s Seattle home on the evening of July 9 standing with his hands in the air and a handgun holstered on his waist.

A neighbor told officers that they heard the man yell, “Go back to India, I’m going to kill you” and saw his vehicle drive by Jayapal’s residence about three times while he yelled profanities, according to legal records. 

The 48-year-old suspect was released from jail Wednesday after police were unable to adequately show he had made the alleged threats, according to the Seattle Times, which reported that law enforcement had obtained a court order requiring the man to surrender his guns, citing concerns about his mental health.

Earlier this month, Rep. Adam Kinzinger (Ill.), one of two Republicans on the House Jan. 6 select committee, shared threatening letters and voicemails he’s received

“I hope you naturally die as quickly as f—— possible,” one caller said.

“Going to come protest in front of your house this weekend. We know who your family is and we’re going to get you,” another caller said. “Gonna get your wife, gonna get your kids.”

The calls were compiled in a video that Kinzinger described in an accompanying tweet.

“Threats of violence over politics has increased heavily in the last few years,” he wrote. “But the darkness has reached new lows.”

According to Pape, the rising threat of violence that he and his colleagues at the Chicago Project on Security and Threats study is not exclusive to the political left or right, with Pape citing as examples the attempt on Kavanaugh’s life and the white supremacist mass shooting in May at a grocery store in Buffalo, N.Y.  

Rather, the issue comprises multiple factors, which Pape analogized to a three-legged stool: These include an individual’s volatility and opportunity to inflict harm, as well as the degree of community support for politically inspired acts of violence.

Although it’s difficult to pinpoint when sympathy for political violence began “seeping into the mainstream,” he said, “we can be confident that these community sentiments for violence are here today.” 

Rep. Mary Gay Scanlon (D-Pa.) attributed much of the trend not only to Donald Trump, who was well known for promoting violence at his rallies and continues to push lies about the election, but also to those Republicans in Congress who continue to defend the former president and his actions surrounding Jan. 6.

“Everybody gets threats these days, and it’s made worse by the fact that certain of our members fail to condemn political violence, particularly when it’s directed at the Capitol, the vice president, the Speaker,” Scanlon said. 

“I only came in in 2018, and the threats that I’ve received have always been in connection to the former president,” she continued. “Certainly we saw a coarsening of public dialogue, a willingness to throw around baseless accusations that the former president supported — modeled as behavior — and I would attribute much of it to his example to the country.”

U.S. government agencies appear increasingly concerned about heightened risk of political hostility in America, as well as the international dimension of the problem. 

The Department of Homeland Security (DHS) has warned that violence in the U.S. is increasingly likely to be politically motivated, a trend that could collide with concerns over the threat from lone actors. 

In a June terrorism advisory bulletin, the agency noted a wide range of divisive topics, from abortion to the border, could be motivators for those likely to use violence to express discontent. It’s something already being played upon by foreign actors.

“Chinese, Iranian, Russian, and other foreign malign influence actors have sought to contribute to U.S. internal discord and weaken its focus and position internationally,” DHS wrote.  

“These actors have amplified narratives that radicalized individuals have cited to justify violence, including conspiracy theories and false or misleading narratives promoting U.S. societal division.”

Rachel Kleinfeld, senior fellow at the Carnegie Endowment for International Peace, told The Hill that the quantity of threats has risen considerably since 2016.

“Violence and intimidation on the right started following the election cycle in 2016. And so we would see justifications for violence among regular people rising at the election period – 2016, 2018 at Trump’s impeachment – obviously at the different events leading up to certification over January 6,” she said. “There’s a sense that this violence is increasingly targeted at politics.”

The authors of a recent book “Radical American Partisanship: Mapping Violent Hostility, Its Causes, and the Consequences for Democracy” found that the share of partisans who say violence by their own party is at least a little justified to advance their party’s goals has risen steadily over recent years, up to around one in five.

Nathan Kalmoe, a professor at Louisiana State University who co-authored the new book with professor Lilliana Mason of Johns Hopkins University, said that polling results varied depending how questions were worded and the severity of violence at issue. But the overall upward trend in public support is clear, he said.

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“Rising favorable views toward violence certainly elevate the risk of more threats and acts of violence against leaders,” Kalmoe said, “and it creates a broader political environment that is more encouraging of extreme political actions.” 

Mike Lillis contributed to this report.