The civil war divided America’s Christians along axes of geography and theology. These days, Donald Trump and Benjamin Netanyahu, soon to be prime minister again, have wrought a similar sorting. In the words of Eric Alterman, “Israel is a red state. US Jewry is blue.”

Alterman is a distinguished professor of English and journalism at the City University of New York. We Are Not One represents four decades of effort, patience and research. Sixty pages of endnotes undergird his arguments, some dating to his student days.

Alterman posits that closeness between the US and Israel has oscillated over time and that younger American Jews, particularly those outside Orthodox Judaism, are now distancing themselves from the Zionist experiment. He relies, in part, on polling by Pew Research.

Practically speaking, the divide may be more nuanced, with the latest shifts also reflecting a response to a rise in crime – and messaging about it. In the midterms, the Republican Lee Zeldin won 46% of Jewish voters in New York as he came close to beating the governor, Kathy Hochul. Donald Trump never surpassed 30% nationally. In 2020, he took 37% of New York’s Jewish vote.

In We Are Not One, Alterman observes how unsafe streets and racial tensions helped spawn neoconservatism. It is “impossible” to separate the movement’s “origins from the revulsions caused by constant news reports of inner-city riots … and broader societal dislocations”. Between 1968 and 1972, Richard Nixon’s share of the Jewish vote doubled from 17% to 35%.

One Saturday night in 1968, a crowd thronged the streets of Borough Park in Brooklyn, a predominately Jewish enclave, to cheer the vice-president, Hubert Humphrey, the Democratic presidential nominee. Over the next four years, “law and order” found purchase. To top it off, George McGovern, the Democratic nominee, made Israel supporters nervous.

The South Dakota senator’s message, “Come home America”, left them wondering if the US would be in Israel’s corner if war came again. Vietnam was a proxy for foreign policy anxieties. As a coda, Alterman recollects how Nixon nonetheless yearned to turn Jews into political foils and whipping boys. That 2016 Trump ad with a six-pointed star over a field of dollar bills? It had deep roots.

Alterman also recounts how Daniel Moynihan, a Democrat, used his position as Gerald Ford’s UN ambassador to reach the Senate in 1976. With support from neoconservatives, hawkish Jews and the New York Times, he beat Bella Abzug, a leftwing lion, in the primary. Then he beat James Buckley, the Republican incumbent.

Moynihan lauded Israel’s raid at Entebbe. In Alterman’s description, he appealed to “American Jews’ feelings of vulnerability and their pride and relief at Israel’s military prowess in kicking the asses” of Palestinian and German terrorists and “humiliating” Idi Amin, Uganda’s “evil dictator”.

Time passes. Things remain the same. In New York, transit crime is up more than 30%. Violence against Jews is a staple, according to the NYPD.

Meanwhile, on college campuses, in Alterman’s words, Israel is a “mini-America”, a useful target for faculty and students to vent against “rapaciousness on the part of the US and other western nations vis-a-vis the downtrodden of the world”.

The author quotes Benzion Netanyahu, the Israeli leader’s late father: “Jewish history is in large measure a history of holocausts.” Modern insecurities spring from ancient calamities.

Kanye West spews bile. Trump entertains him with Nick Fuentes, a white supremacist and Holocaust denier. Republicans quietly squirm. Trump’s Jewish supporters grapple with cognitive dissonance and emotional vertigo. Take Mort Klein, of the hard-right Zionist Organization of America (ZOA), who makes several appearances in We Are Not One.

Testifying before Congress, Klein accused the press of taking Trump’s comments on Charlottesville, where neo-Nazis marched in 2017, “completely out of context”. In 2018, after 11 worshippers were murdered at the Tree of Life Synagogue in Pittsburgh, Klein rode to the rescue again. At the ZOA dinner, he said it was “political blasphemy” to blame Trump.

Last month, ZOA gave Trump its highest honor. According to Klein, the ex-president was the “best friend Israel ever had in the White House”. Then Trump met West, now known as Ye, and Fuentes, twisting Klein into a human pretzel.

“Trump is not an antisemite,” he announced. “He loves Israel. He loves Jews. But he mainstreams, he legitimizes Jew hatred and Jew haters. And this scares me.”

Trump reportedly kept Hitler’s speeches by his bed. If it walks like a duck and quacks like a duck, it’s a duck.

At a recent confab of Agudath Israel of America, an ultra-Orthodox group, Rabbi Dovid Zwiebel, its executive vice-president, condemned Trump: “Yesterday’s friend can be tomorrow’s greatest enemy.” Two years earlier, though, its members clearly backed Trump over Joe Biden. Borough Park was as deep red as Lafayette, Louisiana.

It all carries a whiff of deja vu. Alterman recounts how neoconservatives admonished America’s Jews against complaining of Israel’s alliance with Jerry Falwell and Pat Robertson: “The Christian Zionists’ devotion to ‘Greater Israel’ earned them a pass from the neocons for their occasional outbursts of antisemitism.”

Trump’s Mar-a-Lago dinner created a similar bind. David Friedman, his bankruptcy lawyer and ambassador to Israel, tweeted: “To my friend Donald Trump, you are better than this … I urge you to throw those bums out, disavow them and relegate them to the dustbin of history where they belong.”

Trump was not amused. On Friday, he lashed out at “Jewish Leaders”. Friedman must learn patience. ZOA may wish to rescind its award.

Jason Greenblatt, a Trump Organization lawyer who moved to the White House, echoed Friedman for CNN. Days later, he spoke at a synagogue in Scarsdale, north of New York City. Greenblatt repeated the need for Trump to correct the record and urged those in attendance to politely speak up.

In the next breath, he lauded his one-time boss’s achievements and character. It sure is tough to quit Trump.

• We Are Not One: A History of America’s Fight Over Israel is published in the US by Hachette Book Group