Democrat Zohran Mamdani, elected last November on a left-wing platform and in direct opposition to Donald Trump, officially became mayor of New York on Thursday, where many challenges await him.

In a brief ceremony held in a historic Manhattan subway station, the 34-year-old was sworn in before Letitia James, the Democratic attorney general of New York State and a personal enemy of the US president, whom she had convicted of fraud in 2024.

The city's first Muslim mayor, he swore on a copy of the Quran held by his wife, the artist Rama Duwaji, an edition that had belonged to a Harlem intellectual figure, Arturo Schomburg, a pioneering writer and historian of Black American history, who died in 1938.

"This is truly the honor and privilege of a lifetime," he said.

Highly conscious of symbols, Zohran Madmani justified the choice of a prestigious and disused station - "Old City", with elegant vaults and colorful glass roofs dating from 1904 - by the fact that it embodied in his eyes "a city that dared to be both beautiful" and "capable of transforming the lives of the working classes".

He was inducted shortly after midnight, as thousands of people celebrated the arrival of the new year in Times Square.

This small-scale inauguration ceremony will be followed by another on Thursday at midday at City Hall, presided over by two champions of the American left, Senator Bernie Sanders and Representative Alexandria Ocasio-Cortez.

Tens of thousands of people are expected to attend this large "neighborhood party", with live broadcasts on giant screens, music and performances along Broadway.

Elected on a platform of outright opposition to the American president, particularly on the economy and immigration, Zohran Mamdani has since visited the White House for a surprisingly warm exchange between the two men, who exchanged pleasantries.

- Fight against the high cost of living -

It is not certain, however, that Donald Trump has definitively shelved his threats, made during the campaign, to send the National Guard to New York or to cut federal subsidies to the city.

"If tomorrow Stephen Miller (a close advisor to Donald Trump) or JD Vance (...) suggest to the president that he send more immigration police to New York, he will do it," Lincoln Mitchell, a professor of political science at Columbia University, told AFP.

Furthermore, the new mayor's voters "really expect" him to firmly oppose the White House.

Zohran Mamdani, a young local elected official in the borough of Queens with little political experience, will have a lot of work to do to implement his campaign promises, which have generated great expectations among the population.

With important congressional elections ("midterms") just months away, his successes and failures will also be closely scrutinized by the Democratic camp, which still often seeks inspiration to oppose Donald Trump.

A member of the small Democratic Socialists of America (DSA) party, the Ugandan-born American, who became a naturalized citizen in 2018, has built the core of his program on the cost of living, which has become prohibitive for some of New York's 8.5 million residents, particularly housing.

His predecessor Eric Adams, whose record was marred by accusations of corruption, worked to complicate a flagship measure, the freeze on rents for more than a million apartments, by appointing or reappointing several close associates to the committee responsible for deciding on it.

The details of Zohran Mamdani's other promises—building 200,000 affordable homes, providing childcare for all, opening low-cost public supermarkets, and offering free bus service—are not yet known. But he will have to make announcements soon to implement them.

A long-time supporter of the Palestinian cause, and extremely critical of Israeli policy, the elected official is finally aware that he is being closely monitored on the issue of defending the Jewish community, against a backdrop of rising anti-Semitism in New York and elsewhere in the United States.

Since his election, one of his recruits resigned after the revelation of anti-Semitic tweets she had posted in her youth.

AFP