James will formally swear Mamdani in at midnight when his term officially begins, and Sanders will oversee the mayor-elect`s ceremonial swearing in later that day.

New York City Mayor Zohran Mamdani and Sen. Bernie Sanders, I-Vt., campaigned together earlier this year.Andres Kudacki / Getty Images file

Incoming New York City Mayor Zohran Mamdani will be sworn into office in January by state Attorney General Letitia James and Mamdani`s fellow democratic socialist, Sen. Bernie Sanders, I-Vt.

Sanders will oversee the mayor-elect`s ceremonial swearing in at a New Year`s Day block party, while Attorney General Letitia James will formally swear Mamdani in at midnight when his term officially begins.

In a news release announcing the events, the transition notes that Sanders` "unapologetic progressive values inspired Zohran to run for office in the first place."

"It is an honor to be sworn in by two leaders I have admired for years: Attorney General Tish James and Senator Bernie Sanders. Attorney General James has taken on powerful interests in her defense of New Yorkers and embodied the principle of equal justice before the law," Mamdani said in a statement.

WNYC was first to report that Sanders would swear in Mamdani.

"Senator Bernie Sanders laid the foundations for our movement with his steadfast commitment to the dignity of working people and his belief in a government that serves the many, not just the few. I can think of no better leaders to help usher in a new era for New York City."

Mamdani, who beat former New York Gov. Andrew Cuomo and Republican Curtis Sliwa in last month`s election, is set to become mayor of the country`s largest city on Jan. 1 (and its first Muslim mayor). Mamdani campaigned with Sanders on the trail as he electrified the same progressive electorate locally that the Vermont senator activated in his two presidential bids.

James was one of Mamdani`s most prominent endorsements from a state where many major Democrats tried to keep their distance from the progressive candidate. As the Democratic primary was conducted by ranked choice, which allowed voters to rank up to five candidates (in order of preference), James announced she was ranking Mamdani third on her ballot. In October, James spoke at a rally with Mamdani shortly after she was indicted on fraud charges tied to a mortgage loan (a federal judge later tossed that indictment).

"He is a leader fighting for a better future for this city, and he, like me, knows what it`s like to be attacked, to be called names, to be threatened, to be harassed," James said at the time.