(JTA) — When Brad Lander and Zohran Mamdani were jointly honored at a left-wing Jewish event in September, the two politicians’ alliance was at the center of the evening.

Lander, who had cross-endorsed Mamdani in the Democratic primary months earlier, said he was “proud to be a Jew for Zohran” during his speech at the Mazals gala, hosted by Jews for Racial and Economic Justice. The pair hugged onstage as comedian Ilana Glazer introduced them. The mood was celebratory, albeit sprinkled with cautious reminders that there was still a general election to win.

Nearly two months later, Mamdani fulfilled expectations with an election win. Lander would attend his election night rally, celebrating Andrew Cuomo’s loss with a T-shirt that read “Good f—ing riddance.”

But his future in the city’s new order was uncertain. After Lander reportedly angled for a top position in Mamdani’s City Hall, Mamdani filled out his leadership team with others, leaving Lander in the cold when his tenure as comptroller ends next month. Now, he appears to be considering a run for Congress in his district, setting up a potential rare instance of a Jewish progressive challenging a Jewish centrist.

“I won’t be making any news tonight,” Lander warned with a smile at an event Wednesday night for Standing Together, an Israel-Palestinian peace-building organization. Supporters greeted him after the event, many saying they’d be happy to canvass and vote for him should he run for Congress.

“There are many ways to serve, and I will have more to say about the ones that I am looking forward to in the future,” Lander said in an interview after the event.

Lander told Crain’s New York Business last week that he is “very seriously considering” challenging Rep. Dan Goldman in New York’s 10th Congressional District in next year’s midterm Democratic primary. A poll taken last month suggests that he would stand a strong chance.

Israel would likely weigh heavily in a Lander-Goldman matchup. Lander is a self-described liberal Zionist whose criticism of Israel has intensified since his alliance with Mamdani, a longtime anti-Zionist. Goldman is a moderate who did not endorse in the general election for mayor, saying he was “very concerned about some of the rhetoric coming from Zohran Mamdani,” and that he wanted to see Mamdani condemn “violence in the name of anti-Israel, anti-Zionism.”

The New York Times reported on Friday that Mamdani had urged Lander to challenge Goldman — in the same conversation where he told Lander he wouldn’t be hiring him at City Hall.

The 10th Congressional District covers Lower Manhattan, as well as parts of western and central Brooklyn, where Lander was a three-term City Council member. While Lower Manhattan was more split in the general election, most of the district’s Brooklyn neighborhoods voted overwhelmingly for Mamdani. The district also includes part of Borough Park, a neighborhood with a large Orthodox Jewish population that strongly supported the centrist mayoral candidate, Andrew Cuomo.

There has been an appetite in progressive circles for Goldman to be replaced in 2026 by a candidate more aligned with their politics. “Dump Dan” flyers were handed out to people lining up for Wednesday’s event with Lander, held in a Brooklyn Heights church that falls within the district.

“I would love to see Brad in Congress,” said Arlene Geiger, founder and coordinator of the Upper West Side Action Group, which endorsed Lander in the Democratic mayoral primary.

“I think he’s progressive and Dan Goldman is very tied to AIPAC,” she continued, referring to the Israel lobby that is seen as increasingly toxic by Democrats. “I don’t like his position on the Middle East at all. He’s more of a centrist.”

Geiger’s group is based outside the district, but she said in an interview that it “would be happy to be working” on Lander’s campaign to challenge Goldman.

A September poll by Data for Progress surveyed voters in the 10th congressional district; in a two-man race between Goldman and Lander, the poll found that Lander would win 52-33.

But Democratic strategist Trip Yang advised pumping the brakes, pointing out that polls taken so far in advance of an election “don’t matter as much” and that incumbents bring an advantage. Plus, he noted, City Council member Alexa Aviles, who’s reported to have interest in the seat, could pose an obstacle for Lander.

“In a lot of ways, Alexa Aviles has a higher ceiling as a congressional candidate than Brad Lander,” Yang said, pointing out that 20% of the district is Latino, and that she would likely have the Democratic Socialists of America’s endorsement, giving her more of “the Zohran imprint.”

At first, the DSA privately committed not to endorse any of Lander’s hypothetical opponents, but — after Lander held out while awaiting a potential job under Mamdani — has since voted to back Aviles, a longtime member, the New York Times reported on Friday, adding that multiple sources said Mamdani has said he would back Lander. Maneuvering is reportedly underway within the left-wing group, which counts the mayor-elect as its most prominent member, to avert the progressive split that delivered the seat for Goldman in 2022.

While already a known quantity as the city’s top financial officer, Lander gained “the Zohran imprint” himself by closely associating with the mayoral frontrunner since June. Lander also gained recognition over his recent protests against ICE, for which he was arrested by federal agents at an immigration court.

After finishing third in the ranked-choice primary, Lander actively stumped for Mamdani throughout the general election campaign to help defeat Cuomo a second time.

“I was proud to do that — I have been proud all the way through the general election campaign to campaign with him, side by side,” Lander said this week. He added that he would “continue to work in close partnership” with Mamdani to achieve his campaign goals.

Throughout the election, Lander worked to ease concerns from many Jewish New Yorkers about Mamdani’s position on Israel, including his support for the Boycott, Divestment and Sanctions movement. Lander sought to reinforce Mamdani’s commitment to the safety of Jewish New Yorkers, and showcased the democratic socialist’s engagement with Jewish communities.

He brought Mamdani to the progressive synagogue Kolot Chayeinu, where Lander is a member, for Rosh Hashanah services, and accompanied Mamdani for Kol Nidre services at another progressive congregation.

He spoke highly of Mamdani at the Mazals. “Having an immigrant Muslim mayor with a genuinely inclusive vision — and that brilliant smile — it offers us a chance for us to strengthen what is, for so many of us, so deeply Jewish about this city,” Lander said. “And that’s why I’m proud to be a Jew for Zohran.”

Critics said Lander’s efforts merely “kosherized” antisemitism at a time when fierce reaction to the war in Gaza led to Jews feeling unsafe and isolated, and anti-Jewish attacks rose.

“Lander is part of a larger story of the collapse of New York’s Jewish-political establishment, which has forced Jews to seek representation in non-Jewish politicians who inevitably get told to mind their business when they criticize anti-Semitism,” the conservative pundit Seth Mandel wrote in Commentary in June. “Lander has played an important role in this collapse by being a sherpa of sorts for rising Jew-baiters.”

And as the election wore on, Lander seemingly moved closer toward Mamdani’s positions; he began using the term “genocide” to describe Israel’s military campaign in Gaza — a term he had previously refrained from using — during a Yom Kippur service in October.

Lander credited that shift in terminology to conversations he had with his daughter, who had read Raphael Lemkin — the Holocaust survivor who coined the term “genocide” — in a college class.

“She had read a lot of Lemkin and she brought it forward to me, and pushed me pretty hard,” he said. “And we had a lot of conversation, debate back and forth — we’re not so different from many other families full of liberal Zionist parents and further left kids.”

He added, “You can continue to be a liberal Zionist who believes in the vision of Israel as a Jewish and democratic state, and be honest about what Israel has been doing to Palestinians in Gaza, and the West Bank as well.”

In his efforts to warm Jewish voters to the idea of voting for Mamdani, Lander spoke to groups like the Upper West Side Action Group — which had endorsed him in the primary — and took questions about Mamdani from an audience that was mostly Jewish.

Geiger, the group’s coordinator, said Lander’s endorsement helped grow Mamdani’s support among their voters who were unsure because of the candidate’s stance on Israel, as well as the 34-year-old Assembly member’s lack of executive experience.

“There were those, I think, who were swayed by Brad’s endorsement because they like Brad, and knew him,” said Geiger, who is Jewish.

Yang said he believed that Lander’s advocacy boosted Mamdani’s appeal. “I don’t know if Zohran has this big of a winning margin without Brad Lander,” he said. “You have to give Brad credit for this.”

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