Alexandria Ocasio-Cortez stood on the House floor and implored her colleagues to hold Paul Gosar accountable for sharing an altered anime video showing him killing her and attacking Joe Biden.

“Our work here matters. Our example matters. There is meaning in our service,” Ocasio-Cortez said in her speech last week. “And as leaders in this country, when we incite violence with depictions against our colleagues, that trickles down into violence in this country.”

House Republicans heard Ocasio-Cortez’s impassioned plea and responded with a collective shrug. All but three Republican members voted against censuring Gosar and stripping him of his committee assignments, while every House Democrat supported the resolution.

The Gosar incident served as the latest data point in an alarming trend in American politics. In a year that began with a deadly insurrection at the US Capitol, lawmakers have seen a sharp rise in the number of threats against them. Republicans’ muted response to Gosar’s behavior has intensified fears about the possibility of more political violence in America in the months to come.

Jackie Speier, the Democratic congresswoman who spearheaded the effort to censure Gosar, warned that Republicans’ refusal to hold him accountable could have dangerous repercussions.

“If you are silent about a member of Congress wanting to murder another member of Congress, even in a ‘cartoon’, you are inciting violence,” Speier told the Guardian. “And if you incite violence, it begets violence.”

That cycle is already playing out in the halls of Congress. The US Capitol police reported earlier this year that the agency had seen a 107% increase in threats against members compared with 2020. The USCP chief, Tom Manger, has said he expects the total number of threats against members to surpass 9,000 this year, compared with 3,939 such threats in 2017.

Some of those threats have been on vivid display in the past month. In addition to Gosar’s violent video, the 13 House Republicans who voted in support of the bipartisan infrastructure bill earlier month have received threatening messages.

Representative Fred Upton of Michigan publicly shared one such message, in which a man called the Republican congressman a “fucking piece of shit traitor”. “I hope you die. I hope everybody in your fucking family dies,” the man said in the message.

And those kinds of threats are not reserved solely for members of Congress. Election workers and school board members also say they are receiving more violent messages. According to an April survey commissioned by the Brennan Center for Justice, nearly one in three election officials are concerned about their safety while on the job.

Stephen Spaulding, senior counsel at the government watchdog group Common Cause, described such violent tactics as “a core threat to our democracy”.

“The threat of violence is really to intimidate people from doing their jobs and upholding their oath of office,” Spaulding said. “When you start having these violent episodes enter the system, it is totally counter to the way that we are supposed to engage in open and fair debate about policy issues in this country.”

There are already signs that fears over personal safety are pushing lawmakers out of office. When the Republican congressman Anthony Gonzalez announced in September that he would not seek re-election, he said his vote to impeach Donald Trump for inciting the insurrection had affected the lives of his family members.

Gonzalez told the New York Times that, at one point earlier this year, uniformed police officers had to escort him and his family through the Cleveland airport because of security concerns.

“That’s one of those moments where you say, ‘Is this really what I want for my family when they travel, to have my wife and kids escorted through the airport?’” Gonzalez said.

Even though threats are affecting their own caucus members, House Republicans rejected the opportunity to send a message by voting to censure Gosar. Instead, the House minority leader, Kevin McCarthy, attacked the censure resolution as a Democratic “abuse of power” and suggested he would award Gosar with “better committee assignments” whenever Republicans regain control of the chamber.

“He’s got a number of radical extremists in his caucus that are very effective communicators to the right fringe, and he can’t really rein them in because reining them in means they will attack him,” Speier said. “You might as well put a brass ring in Kevin McCarthy’s nose because they’re pulling him around.”

Dr Joanne Freeman, a Yale history professor and author of The Field of Blood: Violence in Congress and the Road to Civil War, warned that McCarthy’s response to Gosar’s behavior may encourage similar incidents in the future.

After all, there are other historical examples of lawmakers being rewarded for violent behavior, Freeman noted. After Congressman Preston Brooks attacked Senator Charles Sumner with a cane over his anti-slavery views in 1856, he resigned from the House but was then quickly re-elected by South Carolina voters.

“He’s going to be rewarded for it in some ways, and because of that, there will be others that follow in that model,” Freeman said. “It’s a moment that shows how far party is above government and above institutions of government and above institutional stability.”

While acknowledging the possibility of future violence within Congress, Freeman added that the Gosar incident could also provide an opportunity for a course correction in political discourse.

“We’re in a moment of extreme contingency, and indeed things might become much worse,” Freeman said. “But during that kind of moment of extreme contingency where anything can happen, those are also moments where it’s possible to make positive change.”

For Speier, Gosar’s behavior served as a reminder of how far some of her colleagues have strayed from their duties to constituents. The California congresswoman, who announced her retirement last week, urged fellow members to focus on advancing policy rather than spewing violent rhetoric to raise money and rack up retweets.

“I love this institution. It’s such a privilege to serve,” Speier said. “We’re given the opportunity to fashion legislation to make lives better for the American people. And that’s what we should be doing.”