When Brad Lander opened his Democratic primary bid for New York’s 10th Congressional District late last year, he made a promise that would once have meant political suicide: He would not do “AIPAC’s bidding” in Washington.

Now the June 23 primary is almost here, and AIPAC has been a recurring theme throughout the campaign. A progressive Jew and self-described liberal Zionist, Lander challenged his opponent, the pro-Israel incumbent Dan Goldman, to take a “people’s pledge” to limit money from super PACs. He has sent a steady stream of text and email blasts comparing AIPAC with Wall Street and crypto — a new, unholy trinity of corrupting influences in democratic politics.

Goldman, meanwhile, has tried to assert his independence from AIPAC. He accepted its endorsement but has refused money from all political action committees. And he has said he urged AIPAC to break ranks with Israel and criticize its government when appropriate.

The 10th Congressional District, which stretches from downtown Manhattan into parts of brownstone Brooklyn, is one of the country’s most Jewish districts. It would be easy to dismiss AIPAC’s prominent role in the campaign as a parochial, only-in-New York phenomenon. But different versions of it have played out across the country during this primary cycle.

AIPAC — the American Israel Public Affairs Committee — exerts its influence by encouraging members to reject anti-Israel candidates and to support pro-Israel ones through fund-raising emails and its website, where a portal lets donors give the legal maximum to any political campaign. But the group also has a super PAC, the United Democracy Project. Donors can give as much as they want to super PACs, and those PACs can spend as much as they want promoting or attacking individual candidates. AIPAC’s has spent money freely in the Democratic primaries, with mixed results.

It wasn’t so long ago that AIPAC was bipartisan and untouchable, the guardian of America’s close relationship with a key moral and geopolitical ally. For decades after its founding in 1948, most Americans saw Israel as the best of post-World War II liberalism, a democratic Jewish state born out of the ashes of the Holocaust. And AIPAC was its proud American ambassador.