President Donald Trump sharply criticized New York City Mayor Zohran Mamdani over a newly unveiled tax proposal targeting high-value second homes, calling the plan harmful to the city’s future and escalating tensions between the two leaders.

The comments came in response to a proposal announced Thursday by Mamdani and New York Gov. Kathy Hochul that would impose a tax on secondary residences in the city valued at more than $5 million, with the goal of generating significant new revenue.

Trump weighed in on the plan in a post on Truth Social, warning that the policy would accelerate the city’s decline.

“Sadly, Mayor Mamdani is DESTROYING New York! It has no chance! The United States of America should not contribute to its failure,” Trump wrote on the social platform.

“It will only get WORSE. The TAX, TAX, TAX Policies are SO WRONG,” he continued. “People are fleeing. They must change their ways, AND FAST. History has proven, THIS ‘STUFF’ JUST DOESN’T WORK.”

The proposed measure, introduced jointly by Mamdani and Hochul, would apply to high-end second homes across New York City and is projected by its backers to bring in approximately $500 million.

State officials framed the plan as a fairness measure aimed at wealthier property owners who maintain largely unoccupied residences in the city.

“If you can afford a $5 million second home that sits empty most of the year, you can afford to contribute like every other New Yorker,” Hochul said in a statement.

Mamdani, speaking to reporters on Thursday, said the tax is part of a broader effort to address the city’s mounting fiscal challenges, including a projected $5.4 billion budget gap in the upcoming fiscal year.

“We’re talking about the levels of wealth that are storing themselves here in New York City all at the time at which our city is facing a generational fiscal crisis, so I think that this is something worthy of celebration as part of the work that we are doing with the governor,” the mayor told reporters.

Relations between Trump and Mamdani have been marked by sharp rhetoric in the past, with Mamdani referring to Trump as a “despot” during his mayoral campaign and Trump describing the mayor, a democratic socialist, as a “communist.”

Despite those clashes, the two have also held cordial discussions at the White House, including meetings in November and February, where both sides described the conversations as constructive, particularly on issues related to affordability.