As New York City woke up to a new mayor-elect on Wednesday, Jewish groups that spurned Zohran Mamdani faced a decision — how to react to a leader whose staunch criticism of Israel flew in the face of their core beliefs.

Their first responses ranged from despondent to optimistic, with aims from seeking unity to staging a battlefield.

Jonathan Greenblatt, the Anti-Defamation League chief who railed against Mamdani throughout the race, convened a briefing on Wednesday to discuss grappling with the new administration. He announced a “Mamdani Monitor,” a public tracker of Mamdani’s policies and personnel appointments that the ADL viewed as threatening Jewish security.

“We’re deeply concerned about what the next four years could augur for Jewish New Yorkers — the antisemitic language that he has promoted, the antisemitic policies that he’s championed, the antisemitic extremists who he’s known to affiliate with,” Greenblatt said.

Greenblatt cited Mamdani’s support for the Boycott, Divestment and Sanctions movement against Israel and past rhetoric about the Israeli army as evidence that “this mayor will not have our backs.” Under Greenblatt’s leadership, the ADL has narrowed its civil rights mission to focus on combating antisemitism and anti-Zionism.

Mamdani crested to victory as the city’s first Muslim mayor without a majority of Jewish voters, who have split over his staunch criticism of Israel. Early exit polls from CNN indicate that he won just over 50% of voters but only 33% of Jewish voters, while his pro-Israel opponent Andrew Cuomo won nearly twice as many, at 63%.

Greenblatt said the ADL was closely watching Mamdani with a list of demands. Those included no appointments of people with records of antisemitism, NYPD protection for synagogues and Jewish day schools, and “factual, unbiased education about the Middle East” in schools. He also said it was “very important” to maintain NYPD partnerships with Israeli counterintelligence and counterterrorism efforts.

Hindy Poupko, the chief strategy officer at UJA-Federation of New York, also said her organization was preparing to combat potential Mamdani policies that aligned with BDS. She said that UJA hoped to lobby for broadening a state-level anti-BDS order, passed by Cuomo as governor, so that it would apply to New York City.

“We need to expand that Cuomo executive order to cover City Hall, because it would be devastating on many fronts — not to mention economically devastating for New Yorkers — if the Mamdani administration engaged in any kind of BDS activity,” said Poupko.

Asked if they would meet with Mamdani, both Greenblatt and Poupko gave qualified answers.

“I will not meet him on my own,” said Greenblatt. “I think we have a responsibility to our fellowship as Jews. I’m not going to do that meeting without UJA. I’m not going to do that meeting without some spiritual leadership as well.”

Poupko said, “The ball’s in his court.” If Mamdani took actions to “put Jewish New Yorkers at ease,” then she said UJA leaders would meet him.

Mamdani was asked about Greenblatt’s proposed “Mamdani Monitor” in a press conference on Wednesday.

“I think that anyone is free to catalog the actions of our administration,” he answered. “I have some doubts in Jonathan’s ability to do so honestly, given that he previously said I had not visited any synagogues, only to have to correct himself.”

Greenblatt incorrectly stated that Mamdani had not visited “a single synagogue” during a CNBC interview in August. He later said he meant that Mamdani had not visited any synagogues since the June primary.

The ADL and UJA were not alone in mourning Mamdani’s victory. The New York Board of Rabbis and other leading Jewish institutions in the city said in a joint statement, “We cannot ignore that the Mayor-elect holds core beliefs fundamentally at odds with our community’s deepest convictions and most cherished values.” They added that they would continue to work with every level of government.

Rabbi Marc Schneier, who heads The Hampton Synagogue on Long Island and backed Cuomo, said he planned to establish the first Jewish day school in the Hamptons as a haven for “thousands of Jewish families” fleeing “the antisemitic climate of Mamdani’s New York City.”

Meanwhile, the Republican Jewish Coalition called Mamdani’s victory “a deeply distressing result for New Yorkers, particularly Jewish New Yorkers,” and accused his entire party of condoning antisemitism. “There is only ONE party in this country fighting antisemitism and supporting Israel, and it is the Republican Party,” said the coalition.

Other past critics of Mamdani seemed ready to put the election behind them. The pro-Israel billionaire Bill Ackman, whose prolific and protracted attacks on Mamdani during the campaign often predicted an apocalyptic city under his leadership, appeared to offer an olive branch just hours after predicting Cuomo would prevail.

“Congrats on the win,” Ackman said to Mamdani on X. “Now you have a big responsibility. If I can help NYC, just let me know what I can do.”

Some voices emphasized mending the divisions that roiled Jewish communities throughout the race. The Union for Reform Judaism, which urged its rabbis not to endorse candidates despite intense pressure from congregants, pressed Jews to “help lower the temperature, listen generously, and take steps to promote healing” in the aftermath of the election.

“Reasonable people across the political spectrum — and across the Jewish community — must aspire to respectfully disagree, and we will do our part to bring people together without erasing real differences,” the group said. They added that they welcomed cooperation with Mamdani and would hold him accountable to “his commitments to protect Jewish communities and all New Yorkers.”

Noting that City Hall does not have a foreign policy, the organization said it would “not hesitate to push back if anti-Israel policies or rhetoric make Jewish New Yorkers who are deeply attached to Israel more anxious and less safe.”

Other Jewish leaders are looking toward a future under Mamdani not with dismay or caution, but with jubilation. Activists from left-wing groups like Jewish Voice for Peace and Jews for Racial and Economic Justice, which have bolstered Mamdani’s rise to power, celebrated the victory at his watch party on Tuesday night. Several people there told the Jewish Telegraphic Agency they would finally have an ally in City Hall who aligned with their views on issues from income inequality to Palestinian rights.

Rabbi Lauren Grabelle Herrmann, who leads the SAJ synagogue on the Upper West Side, urged congregants with wide-ranging reactions to the election to keep in mind their shared hopes for the well-being of all Jews and New Yorkers.

She quoted the prophet Jeremiah, writing, “Seek the welfare of the city to which I have exiled you and pray to God on its behalf; for in its prosperity you shall prosper.”