There is a deadly outbreak of anti-Semitism in America.

On Saturday, a gunman opened fire on the congregants of the Tree of Life synagogue in Squirrel Hill, a Pittsburgh suburb. The alleged culprit, a 46-year white man, killed 11 congregants and wounded six more people, including four police officers. Witnesses reported that the murderer shouted "All Jews must die!" in the process.

It was the deadliest single act of anti-Semitic violence in American history.

As usual, people looked for motivating factors afterwards. In this case, they did not have to look far. The alleged killer was apparently obsessed with racist anti-refugee rhetoric and anti-Semitic conspiracy theories — things that are increasingly winked at, tolerated, and even promoted at the very highest levels of conservative politics, up to and including Fox News and President Trump.

The American right has a severe anti-Semitism problem, and the results speak for themselves.

Just before the shooting, the suspected killer apparently posted the following on Gab, a Twitter-style social media site often utilized by racists: "HIAS likes to bring invaders in that kill our people. I can't sit by and watch my people get slaughtered. Screw your optics, I'm going in." This is a reference to the Hebrew Immigration Aid Society, a group founded to help all refugees in memory of the Holocaust, when most nations, including the United States, turned away most Jewish refugees. (Among many others, the group helped settle Google co-founder Sergey Brin.)

The word "invaders" is almost certainly a reference to the refugee caravan making its way up through Mexico, which was another subject of obsessive hatred for the suspect. The logic of the shooting, apparently, was to kill Jews at random to stop them from helping refugees enter the United states.

This logic follows the implications of the racist hatred that conservative media and Republican politicians from Trump on down have been whipping up against the refugee caravan this month — and it has not stopped since the shooting. On Monday, Trump baselessly warned that the caravan was full of "Gang Members," while Fox News' Brian Kilmeade speculated that it might be filled with diseases.

Additionally, Trump, House Majority Leader Kevin McCarthy (R-Calif.), Rep. Matt Gaetz (R-Fla.), Rep. Louis Gohmert (R-Texas), and numerous Fox News hosts have spread the anti-Semitic conspiracy theory that Jews — specifically George Soros, who was the target of a different right-wing terrorist attack recently — are somehow masterminding the caravan. A few days before the shooting, a guest on Lou Dobbs' Fox Business show referred to the "Soros-occupied State Department," a conspiracy theory about secret Jewish control of government that comes straight out of the Protocols of the Elders of Zion, as Josh Marshall points out.

This puts the infamous "Jews will not replace us" chant from the fascist hate mob in Charlottesville last year (where, let us not forget, leftist protester Heather Heyer was murdered in cold blood) in new light, as Paul Krugman explains. The racist conspiracy theory here is not that Jews themselves will displace whites, but that they will secretly connive to bring in so many immigrants and refugees that whites will become a minority population.

Similarly, after the "MAGABomber" attempted to blow up Soros' house, Florida Republican gubernatorial candidate Ron DeSantis suggested that Soros might be planting deep cover agents in Florida's state government.

It's impossible not to notice the jarring contrast between these conspiracy theories and the actual victims of the synagogue shooting, who were about as far from being global political titans as it is possible to imagine. On the contrary, a gutting profile of two of the victims revealed two brothers with mild mental disabilities but hearts as big as the sky — men who loved nothing more than volunteering at the synagogue and helping other disabled folks. Of one, Cecil Rosenthal, a friend remembered that as a basketball coach he insisted on cheering for both teams at a game. "They're all my friends," he said.

The clearest evidence of the anti-Semitic undertones of the constant Republican fulmination over George Soros is the utter moderation of his politics. Far from being some secret socialist mastermind, Soros is merely one of dozens of milquetoast big donors to Democratic Party politicians and anodyne political causes. His politics are to the left of Bill Clinton, but he is not even much of a fan Bernie Sanders, let alone antifa or other actual radical groups. Yet he gets probably 100 times the attention and hatred from conservative media than any other liberal donor, and it couldn't be more obvious why. As Spencer Ackerman points out, it follows previous episodes of anti-Semitic hysteria about rich Jews to a T.

Nevertheless, no simple empirical fact is going to put a dent in this kind of iron propaganda dome. Just as hysterical Nazi propaganda about Jewish conspiracies ended with Germany massacring helpless, impoverished Polish peasants, the fact of a shooter murdering two of the sweetest, gentlest men in all of America will make no difference at all to committed anti-Semitic extremists. As historian Eric Hobsbawm wrote:

Fascism was triumphantly anti-liberal. It also provided the proof that men can, without difficulty, combine crack-brained beliefs about the world with a confident mastery of contemporary high technology. [The Age of Extremes]

Anti-Semitism and other rancid bigotries are thriving on the right because they serve an important political function: They paper over the cracks between the Republican Party elite's unpopular and hideously corrupt policy record, and their voting base of credulous, aging whites who are terrified of change. Elected Republicans are, as usual, keeping their heads down and hoping for a change of subject. Don't let them get away with it.