New York City Mayor Zohran Mamdani and U.S. President Donald Trump in the Oval Office. Jim WATSON / AFP via Getty Images

President Donald Trump once cozied up to New York City Mayor Zohran Mamdani last year in the Oval Office. Now, he might attempt to block one of Mamdani’s top priorities from succeeding.

The president said on Monday that he was weighing whether he’d step in to block a proposal from Mamdani that would impose a tax on ultra-wealthy New Yorkers with second homes worth at least $5 million.

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“I am looking to see if the Federal Government has any legal right to avert this disaster, before it is too late,” Trump wrote in a Truth Social post. “This doesn’t work in America, and must be stopped, NOW!”

Trump also labeled the tax as a “dangerous political ‘experiment'” which would “destroy” New York City.

The levy is already at the center of a legal battle with a Staten Island judge ordering an emergency delay on Monday after a trio of homeowners filed a lawsuit to challenge implementation of the tax. They argue the burden is falling on property owners to demonstrate they don’t have to pay the tax rather than local officials determining who are the affected taxpayers first.

The New York City government quickly filed a motion to seek an appeal, placing the judge’s order on hold.

The annual tax would affect high-value residential properties in New York City as long as they are not a primary residence or occupied by the owner’s family. It would also apply to condos and co-ops worth more than $1 million.

The origins of the tax

New York Gov. Kathy Hochul first proposed it in April with the intent of generating revenue to finance essential services in New York City, such as affordable child care. Mamdani was quick to endorse it as a key piece of his progressive agenda to tax the wealthiest New Yorkers. State officials estimate the tax will bring in at least $500 million per year and help close New York City’s budget gap.

Mamdani’s press office didn’t immediately respond to a request for comment. He said on Monday that his administration was ready to defend the measure in court.

“We are confident in our position,” Mamdani said at a news conference. “And that is a confidence coming from both the legality of the City’s actions as well as the importance of a surcharge on secondary homes worth more than $5 million, a surcharge that will help fund safer streets, that will help fund stronger schools, and it will help fund the city that New Yorkers deserve.”