After James T. Hodgkinson opened fire Wednesday morning during a congressional baseball practice in Alexandria, Va., it didn't take long for partisan vitriol to erupt.
Despite calls for bipartisan unity from congressional leaders, far-right voices on social media blamed the attack on anti-Republican political rhetoric.
Hodgkinson, who was shot and killed by police, ranted against President Trump on his Facebook page and was an ardent supporter of Sen. Bernie Sanders, D-Vt. Rep. Jeff Duncan, R-S.C, said prior to the shooting, Hodgkinson asked him if the players on the field were Republicans or Democrats.
For many Twitter users, those facts were proof that the shooter was provoked by anti-Trump celebrities, artists, politicians and pundits such as Kathy Griffin, who held aloft a mock decapitated Trump head in a photo shoot, and the Trump-like Julius Caesar performed in Central Park.
The "resistance," they declared, has blood on its hands.
When you continue to mainstream this kind of hatred you get Alexandria...it all comes from the incitement by the Left and the media. pic.twitter.com/9sh7WWYle7— Nick Short (@PoliticalShort) June 14, 2017
"This could be the first political rhetorical terrorist act and that has to stop," said. Rep. Rodney Davis, R-Ill. "I believe that there's such a hatefulness in what we see in American politics and policy discussions right now, and in social media and the 24-hour news cycle."
Ann Coulter added late-night TV hosts among the guilty as well.
"The explosion of violence against conservatives across the country is being intentionally ginned up by Democrats, reporters, TV hosts, late-night comedians and celebrities, who compete with one another to come up with the most vile epithets for Trump and his supporters," the conservative firebrand wrote on her website.
15 Times Celebrities Envisioned Violence Against Trump and the GOP https://t.co/TXaO26Pzgr— Stefan Molyneux (@StefanMolyneux) June 14, 2017
But most experts agree that as contentious as American politics have become, psychological issues, not politics, are the primary reasons a troubled person would commit a violent act.
"People who are prone to this kind of violence will find justification for acting out from religion, from politics, from whatever," said Peter Ditto, a professor of psychology at the University of California-Irvine. "I don't think that it's fair to say all this political conflict that we're going through is going to make a lot of people go out and shoot people."
It wasn't just Wednesday, and it wasn't just Republicans
Shortly after Wednesday's shooting, HuffPost reported Rep. Claudia Tenney, R-N.Y., received a threatening email reading, "Do you NOT expect this? When you take away ordinary peoples very lives in order to pay off the wealthiest among us, your own lives are forfeit. Certainly, your souls and morality were lost long before. Good riddance.”
But conservatives are not the only ones feeling threatened. Just this month, two Democratic political candidates withdrew from races citing fears for their safety.
Kim Weaver, who was running for Congress in Iowa against Republican Steve King, said in a Facebook post that she "received very alarming acts of intimidation, including death threats. While some may say enduring threats are just a part of running for office, my personal safety has increasingly become a concern.”
Michael Treiman, a Democratic running for mayor of Binghamton, N.Y., also dropped out of the race after he said he received emails which he characterized as "heinous attempts to scare me off," including threats against his wife and 2-year-old and 11-month-old children.
Violent and divisive rhetoric has been part of American political history since the country's founding. From the Revolutionary War through the Civil War and the street battles over Vietnam and Civil Rights, the U.S. has experienced many periods of vitriolic, partisan hate and anger.
"You can go back to the election of 1800 between Jefferson and Adams and find a whole lot of quite outrageous statements made on both sides," said Martin J. Medhurst, a professor of rhetoric and communication at Baylor University. "The same is true throughout American political history. We had one guy, [Charles] Sumner, who was caned on the floor of the Senate and almost killed. We have a long history of violence in this country, both rhetorical and otherwise."
Many comparisons were drawn between Wednesday's attack and the attempted assassination of Arizona Democratic Rep. Gabrielle Giffords in 2011. At that time, Democrats levied the same claims about nasty political rhetoric against the right. Several commentators said 2008 vice presidential candidate Sarah Palin had encouraged violence against Democrats by posting a campaign map with crosshairs on 20 Democrat-held congressional districts. Giffords' was one of them.
Echo chambers and anonymity
Partisanship and political animosity have spiked since the mid-1990s, according to a June 2016 survey from the Pew Research Center.
"Majorities in both parties express not just unfavorable but very unfavorable views of the other party," the survey found. "And today, sizable shares of both Democrats and Republicans say the other party stirs feelings of not just frustration, but fear and anger."
While incendiary rhetoric has always been part of American politics, experts say the Internet, social media and the polarized news media have contributed to increasingly partisan and toxic political discourse.
"I think what has changed in the 21st century is the nature of the different media of communication and especially the rise of social media, where people apparently believe that they can pretty much say anything," Medhurst said.
Yphtach Lelkes, a professor at the University of Pennsylvania's Annenberg School for Communication, said there are two main reasons social media is contributing to increased partisanship: the echo chamber and anonymity.
"We're sorting in two different tribes, and when you're doing that there are psychological processes that will almost spontaneously or immediately trigger feelings of warmth toward your own group and often feelings of hostility toward the other group," Lelkes said. And, "because social media, and the Internet in general, is often anonymous, it facilitates more uncivil, inflammatory remarks."
Ditto calls it "group polarization effect."
"Now you come home and if you're a liberal you go to MSNBC and if you're a conservative you go to Fox News," he said. "You read different newspapers, you go to different websites and all you hear is your side of the story."
But political passion does not mean someone is more inclined to political violence, according to Nathan Kalmoe, an assistant professor of political communication at Louisiana State University who has studied the relationship between rhetoric and violence. In fact, Kalmoe's research found that people who are highly partisan strongly favor change through the democratic process and "are less likely to endorse or support political violence by citizens against political leaders."
PHOTOS: Multiple people shot at Congressional baseball practice
"Political rhetoric can make a difference, especially in people’s attitudes about the appropriateness of violence in politics," he said, but it would not "be the main factor that drives people to violent acts."
'This has got to stop'
It's easy for people to become trapped in an escalating cycle of political anger, Ditto said.
"We're fighting about issues that we care about a lot," he said.
A horrific event like Wednesday's shooting, he added, can either lead the country to further division, or it can make people take a step back from the brink of political hatred.
When Congressman Davis decried Hodgkinson's attack as a "rhetorical terrorist act" he added a call for an end to politically driven hate.
"This has got to stop," Davis said. "We can disagree on how to govern — that's what makes our country great. I'm here because we're all Americans. And I think Republicans and Democrats need to use this day today to stand together and say stop. Let's work together, let's get things done. We can have our differences, but let's not let it lead to such hate."