Members of the US House of Representatives will now receive up to $10,000 to upgrade security at their homes in the face of rising threats against lawmakers, the House sergeant at arms announced last week, in yet another sign that American politics has entered a dangerous, violent new phase.

As support for political violence appears to be on the rise in the US, experts warn that such threats endanger the health of America’s democracy. But they say the country still has time to tamp down violent rhetoric if political leaders, particularly those in the Republican party, stand up and condemn this alarming behavior.

The announcement over increasing security for people in Congress came days after a man attacked Lee Zeldin, a New York congressman and Republican gubernatorial candidate, with a sharp object during a campaign event.

Two weeks before that, a man was arrested outside the home of Pramila Jayapal, chair of the Congressional Progressive Caucus, for allegedly shouting racist obscenities and threatening to kill her. Last month, authorities filed federal charges against a man who they say traveled from California to Maryland with the intent of murdering the supreme court justice Brett Kavanaugh.

Public service has clearly become an increasingly dangerous endeavor in America.

Recent polls show an increasing number of Americans are comfortable with political violence, although there is a wide range of opinions on the type of violence that is acceptable.

According to a mega-survey conducted by researchers at University of California, Davis, and released this month, one in five US adults say political violence is justified at least in some circumstances. A much smaller portion of survey respondents, 3%, believe that political violence is usually or always justified.

Liliana Mason, a political science professor at Johns Hopkins University and co-author of Radical American Partisanship: Mapping Violent Hostility, Its Causes, and the Consequences for Democracy, said the phrasing of survey questions on political violence can drastically affect results. But having studied such polling since 2017, Mason said it is clear that support for political violence is indeed on the rise in the US.

“I think of it as pretty low numbers of people who actually approve of violence at all,” Mason said. “The problem is that, if you go from 7% to 20%, that means that there are certain social spaces where the norms around anti-violence are eroding.”

The impact of that trend can be seen at every level of American government, from the halls of Capitol Hill to local polling places.

The US Capitol police reported 9,625 threats and directions of interest (meaning concerning actions or statements) against members of Congress last year, compared to 3,939 such instances in 2017.

The members of the House select committee investigating the January 6 insurrection have frequently been the targets of violent threats, requiring them to get personal security details.

One member of the committee, Republican Adam Kinzinger, recently shared a threatening letter sent to his wife last month. The sender vowed to execute Kinzinger, his wife and their newborn son. He is not seeking re-election in 2022.

Even those who help administer elections in the US have reported an increase in threats against them. According to a poll conducted by the Brennan Center for Justice this year, one in six elec­tion offi­cials have received threats because of their job, and 77% believe threats against them have increased in recent years.

Jennifer McCoy, a political science professor at Georgia State University whose research focuses on polarized democracies, said: “The kinds of threats and intimidation to … election administration officials and poll workers is very concerning and is also new.”

The apparent increase in threats against public servants has sparked broader concerns about the health of American democracy, particularly in the wake of the January 6 insurrection.

“There is simply no place for political violence in a healthy democracy. The increase in threats and harassment being leveled at people across our government is deeply concerning,” said Jennifer Dresden, policy advocate for the group Protect Democracy.

“To be clear, we’re not yet at a point where political violence has fundamentally undermined our democracy. But when violence is connected to other authoritarian tactics, like disinformation and efforts to corrupt elections, that sets a dangerous path for our democracy that we cannot ignore.”

While threats and harassment against lawmakers and political candidates appear to have increased across many government institutions, they are not evenly distributed.

One study of online messages sent to 2020 congressional candidates found that women, particularly women of color, were more likely to be the target of abusive content. Of all the candidates reviewed, the progressive congresswoman Ilhan Omar, who is Somali American, received the highest proportion of abusive messages on Twitter. Fellow progressive congresswoman Alexandria Ocasio-Cortez, who is Puerto Rican American, saw the most abusive comments on Facebook.

Women of color serving in Congress have spoken publicly about the threats they face, which have become a regular part of their lives on Capitol Hill.

Congresswoman Jahana Hayes, who is Black, told PBS Newshour last year: “I remember, at the beginning of the 116th Congress [in 2019], when we were just spotlighting and highlighting the beautiful diversity of this incoming Congress, but then, on every caucus call, we had members who were getting death threats on a daily basis.”

The acts of political violence carried out in the US are also unevenly distributed across the ideological spectrum. According to a study conducted by the Anti-Defamation League, rightwing extremists have committed about 75% of the 450 political murders that occurred in the US over the past decade. In comparison, Islamic extremists were responsible for about 20% of the murders, while leftwing extremists were blamed for 4% of the killings.

Expert argue the frequency of rightwing violence compared with leftwing violence can be partly explained by Republican leaders’ failure to condemn threatening rhetoric.

“We see justifications for violence that are similar on the left and right,” said Rachel Kleinfeld, a senior fellow at the Carnegie Endowment for International Peace who studies political conflict. “But we see incidents of violence that are vastly higher on the right and that has to do with all of the normalization of violence from leaders on the right.”

That normalization has been on vivid display over the past couple of years in the US. Donald Trump infamously referred to his supporters who carried out the deadly January 6 insurrection as “very special”, telling them: “We love you.” Trump was impeached by the Democratic-controlled House for his role in the 6 January riot, but acquitted in the Senate.

Last year, House Democrats, over near-unanimous Republican opposition, voted to strip the far-right congresswoman Marjorie Taylor Greene of her committee assignments, after it was discovered that she had previously expressed support for assassinating Barack Obama and the House speaker, Nancy Pelosi.

In November, Congressman Paul Gosar received the same punishment, as well as a House censure, after he shared an animated video depicting violence against Joe Biden and Ocasio-Cortez. Only two Republicans supported the censure.

Most recently, the Senate candidate Eric Greitens was widely criticized for airing a campaign ad that appeared to encourage violence against more moderate Republicans. In the ad, Greitens, who resigned as Missouri governor over allegations of sexual harassment, is seen carrying a shotgun and bursting into homes as he urges the “hunting” of Rinos, meaning Republicans in Name Only.

Research indicates that the messages supporters receive from their political leaders have a large impact on whether they actually carry out violent acts, several experts said. In experiments conducted by Mason and her colleagues, some participants were asked to read a quote from Biden or Trump condemning violence while others read nothing. Those who had read the quote were significantly less approving of violence.

“Leaders are actually uniquely powerful in being able to tamp down violence,” Mason said. “Republicans in particular are not using that power. And they could, but they’re not.”

Although political leaders are particularly powerful when it comes to reducing violent rhetoric, Mason’s research indicates that average people may have some leverage of their own. Mason’s team saw some positive results when they asked participants to read messages from random Twitter users condemning political violence. For the overwhelming majority of Americans who oppose such violence, the findings could offer some hope.

“For Americans in general, I think it’s sort of empowering to know that every single one of us has the potential to reduce violence by simply rejecting it,” Mason said. “We can all do that. All the 80% of us who don’t think violence is acceptable have a real voice, and it’s important to use it.”