The president’s tone has come under scrutiny after the Pittsburgh massacre of 11 Jews and ‘does not discourage people from acting out their terrifying views’

Donald Trump has fuelled a climate of hatred in general and antisemitism in particular, with the Republican party acting as his enabler, experts warned on Monday.

The US president’s tone has been under renewed scrutiny after Saturday’s massacre of 11 worshippers at a synagogue in Pittsburgh, believed to be the deadliest attack on Jewish people in American history.

“He has dramatically elevated the level of rhetorical tension in ways that do not discourage people from acting out their terrifying views,” said David N Myers, a professor of Jewish history at the University of California, Los Angeles.

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Trump renewed the offensive on Monday with a tweet that warned of an “invasion” of immigrants, echoing the hate-filled writings of accused synagogue gunman Robert Bowers.

The president wrote that “some very bad people” were mixed into the caravan of several thousand people, mainly from Honduras, currently travelling through Mexico. “This is an invasion of our Country and our Military is waiting for you!” Trump added.

Citing official sources, the Wall Street Journal reported that the Trump administration was preparing to send 5,000 more US troops to the border to help with security, angering immigrants’ rights activists and others who say the move militarizes the issue unnecessarily for political gain ahead of crucial midterm elections next week.

But Trump’s choice of words also caused outrage.

Two hours before he burst into the synagogue and killed 11 worshippers, Bowers posted on the chat site Gab.com about the Hebrew Immigrant Aid Society (HIAS), a not-for-profit organisation that helps refugees relocate to the US. “HIAS likes to bring invaders in that kill our people,” he wrote. “I can’t sit by and watch my people get slaughtered. Screw your optics, I’m going in.”

As the president again tried to shift blame to the media on Monday, arguing that “fraudulent” reporting was contributing to anger in the country and declaring that the press was the “true Enemy of the People”, criticism of his corrosive rhetoric and fears over its consequences were growing.

A survey by the Public Religion Research Institute found a majority (54%) of Americans feel Trump’s decisions and behaviour have encouraged white supremacist groups, compared with 39% who say they had had no effect and 5% who say he has discouraged these groups.

Critics say he has a history of using Jewish stereotypes.

In 2015, he told the Republican Jewish Coalition “I’m a negotiator like you folks” but suggested they would not support him “because I don’t want your money”. The following year, he tweeted an image of Clinton set against a background of US currency with a six-pointed star (reminiscent of the star of David) and the words, “Most corrupt candidate ever!” His closing campaign ad railed against “global special interests” and featured images of George Soros, a billionaire investor and philanthropist, and the Federal Reserve chairwoman, Janet Yellen, both of whom are Jewish.

Facebook Twitter Pinterest A tweet depicting Hillary Clinton and a six-sided star that Trump deleted from his account followed by its replacement, which uses a circle. Photograph: Screengrab

Trump’s first chief strategist was Steve Bannon, a champion of the alt-right. The White House issued a statement to commemorate International Holocaust Remembrance Day that made no mention of Jews or antisemitism. Then the press secretary, Sean Spicer, was forced to apologise after asserting that Adolf Hitler, who gassed millions of Jews during the Holocaust, did not use chemical weapons.

Perhaps most strikingly, after white supremacists marched in Charlottesville, Virginia, wielding flaming torches and shouting, “Jews will not replace us” ahead of deadly violence, Trump said there were some “very fine people on both sides”.

Myers said: “There is a toxic culture of vilification and demonisation that has pervaded American political culture in recent years. Donald Trump did not invent that toxic culture but he has certainly stirred the pot considerably.”

Jewish people make up only about 2% of the US population, the Associated Press reported, but in annual FBI data they repeatedly account for more than half of Americans targeted by hate crimes committed due to religious bias. The Anti-Defamation League identified 1,986 antisemitic incidents last year, up from 1,267 in 2016.

Trump has also made derogatory comments about women, Mexicans, Muslims and others. Myers added: “He’s an equal opportunity and equal opportunistic vilifier. My surmise is that he doesn’t dislike Jews more than other people but I am stupefied by his unwillingness to call it out when it occurs, especially given his own family background with his son-in-law and daughter.”

Ivanka Trump converted to Judaism ahead of her 2009 wedding to Jared Kushner. The couple are practising modern Orthodox Jews.

The Republican party has done little to curb Trump’s tendencies. Last week Kevin McCarthy, the House majority leader and a close ally of the president, posted and later deleted a tweet suggesting that Soros and two other Jewish billionaire Democratic donors were attempting to “buy” the midterm elections.

Myers said: “The party has enabled his behaviour and that is simply unacceptable. They need to insist he take a much more active stance in calling out this kind of violence and that which precedes it.”

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Sara Lipton, a professor of history at the State University of New York, Stony Brook, said “there is absolutely no question” that Trump is aware his followers include white supremacists, racists and antisemites and that he is determined to keep them. The Republican party’s willingness to put power before principle is “even more alarming”, she added.

“This is where I see the breakdown of society: the passivity and tacit acceptance of those in positions of influence.”

Kurt Bardella, a political columnist and former Republican congressional aide, said: “The Republican party has doubled down on its strategy of hiding from all these things. I don’t see them lining up on Fox News to denounce [broadcasters] Lou Dobbs or Rush Limbaugh for spreading rightwing conspiracy theories.

“They have chosen to be cowards in the face of these atrocities and hopefully there will be a reckoning next week when they come before voters.”