On Tuesday, voters in New York’s 16th Congressional District will cast ballots in the most expensive House primary race in American history, and if the polls are right, Representative Jamaal Bowman, a left-wing Democrat, is going to lose. In the primary four years ago, Bowman rode the insurgent energy of the Black Lives Matter movement to an upset victory against a longtime incumbent, Eliot Engel, one of Congress’s most reliable supporters of Israel. But the urgent utopian hopes of that moment have long since faded. Now Israel’s champions, many of whom have never been comfortable with Bowman, are striking back, capitalizing on a political environment transformed by Oct. 7.

Bowman’s challenger is the Westchester County executive, George Latimer, who refuses to criticize Prime Minister Benjamin Netanyahu of Israel, putting Latimer not just to Bowman’s right but also to the right of President Biden and Senator Chuck Schumer, the majority leader. A June Emerson poll showed Latimer leading by 17 points. If Bowman is defeated, he will be the first member of the Squad — a group of young, very progressive Black and brown members of Congress — toppled by a moderate. Given that the American Israel Public Affairs Committee’s super PAC has poured more than $14.5 million into the race, a Bowman loss will probably serve as a warning to other politicians about the cost of breaking with Washington’s pro-Israel political consensus.

“This is, in my view, one of the most important elections in the modern history of this country,” Senator Bernie Sanders of Vermont said at a rally for Bowman on Friday, speaking about the obscene sums being marshaled on Latimer’s behalf. I think Sanders was exaggerating, but the contest is probably the most important congressional primary this year. It’s setting a precedent for big money interference in local politics and tearing at the longtime progressive alliance between Black people and Jews. It could intimidate into silence Democrats who have qualms about Israel’s treatment of the Palestinians, or if Bowman manages an upset, it could embolden them. These high stakes make his carelessness in giving his enemies ammunition especially frustrating.

It was always going to be hard, after Oct. 7, for Bowman to bridge the gulf between his convictions and the expectations of many of his Jewish constituents. His district, which includes a small slice of the Bronx as well as the suburbs of southern Westchester, is among the country’s most Jewish, and many of his voters, traumatized by Hamas’s attack on Israel and by increasingly visible antisemitism in America, wanted someone who would stand resolutely with the Jewish state. Bowman was never going to do that; he was horrified by his encounter with Israel’s occupation during a congressional trip in 2021, and he’s been anguished by the mass death and suffering of Palestinians in Gaza, where he believes Israel is committing a genocide. There is something deeply admirable about his refusal to subordinate his values to political expediency.