Mayor Zohran Mamdani appealed a court ruling Tuesday that would require New York City to expand its CityFHEPS housing voucher program, breaking sharply from a promise he made as a candidate to fully implement the expansion.

The appeal, filed with the Court of Appeals, the state’s highest court, asks judges to overturn a ruling from a lower appellate court that had sided with housing advocates and the City Council. The Mamdani administration is now arguing that the City Council lacked the authority to expand the program in the first place, a position that puts the mayor in direct opposition to the very body that voted to broaden the vouchers three years ago.

The reversal has stunned advocates who had seen Mamdani’s candidacy as a turning point for low-income New Yorkers struggling to stay housed.

CityFHEPS allows roughly 68,000 households to pay about a third of their income toward rent, helping people move out of shelters and into permanent housing. The program’s costs have grown dramatically, from approximately $26 million in 2019 to nearly $1.8 billion last year. That price tag sits at the center of the mayor’s argument for slowing down.

The City Council passed legislation in 2023 to expand eligibility for the vouchers, but former Mayor Eric Adams refused to implement those laws. The Legal Aid Society sued in state court, with the City Council joining as a party. Adams initially won at the trial level, but an appellate court reversed that decision, ordering the city to move forward with the expansion.

Mamdani, then a candidate, had promised to implement the expanded program. Once in office and facing a multi-billion-dollar budget gap, he announced in February that his administration would seek a negotiated settlement rather than full implementation. That was already a step back from his campaign position. Tuesday’s appeal to the state’s highest court moves the goalposts further still.

Joe Calvello, a spokesperson for Mamdani, said the administration remains committed to a settlement and to a “rental assistance program that is sustainable for the long term.”

“This is not the end of negotiations,” Calvello said. “As the budget process advances, we will continue working toward a resolution while advancing a comprehensive, whole-of-government response to the city’s housing and homelessness crisis.”

Housing advocates were not moved by that framing.

Christine Quinn, president of Win, a shelter and supportive housing provider, called the decision a betrayal. “The city’s failure to settle its challenge to codified CityFHEPS expansions is nothing short of a betrayal,” Quinn said in a statement.

Redmond Haskins, a spokesperson for Legal Aid, said the city’s legal reasoning was “unsound” and called the appeal “regrettable.” He said the organization remains committed to securing an outcome that serves New Yorkers who are experiencing homelessness or on the brink of it.

“While we are disappointed that the Administration filed its appeal, we remain committed to securing an outcome that best serves New Yorkers experiencing or on the brink of homelessness and who deserve the means to stay safely in their homes or secure long-term, affordable housing,” Haskins said.

The administration is threading a needle that looks increasingly difficult to thread. Mamdani ran as the candidate who would finally deliver on housing promises the city had made and then abandoned. He won on that message. Now, less than a few months into his term, he is asking the state’s highest court to rule that the City Council never had the right to make those promises into law.

Budget pressures are real, and the cost of CityFHEPS is not a fiction. Any mayor sitting across from a billion-dollar gap has to make hard calls. But there is a difference between renegotiating the pace of implementation and asking a court to invalidate the underlying legal authority of the council entirely. The first is governance. The second is retreat.

The settlement talks, the administration insists, are still alive. For the 68,000 families whose housing stability depends on this program, and for the thousands more who stood to benefit from the expansion, that assurance will need to become something more concrete, and soon.