New York City is leading a coalition of cities and counties that sued the Trump administration Monday over an immigration rule that would widen the list of public benefits federal officials may weigh against green card applicants.

Mayor Zohran Mamdani announced the filing at an 11 a.m. news conference with state Attorney General Letitia James. The rule takes effect Sept. 18. Chicago, San Francisco, Seattle, Santa Clara County, King County in Washington state and the Public Rights Project joined the city's case, NewsNation reported.

The public charge test has existed for more than a century. It allows the federal government to deny visas and green cards to applicants officials believe are likely to depend on public support. The administration wants to expand the range of benefits that count toward that judgment.

Mamdani said the change is "intentionally vague as a means of creating uncertainty and fear," according to Fox News. He said citizens and people seeking humanitarian relief such as asylum are not covered by the rule. Families who remain fully eligible for benefits will still stop using them, he argued, because they will not know where the line falls.

James filed a second challenge on behalf of the state. She is leading 21 other states and the District of Columbia in asking the U.S. District Court for the Southern District of New York to block the rule before Friday, Fox News reported.

The mayor tied the case to health care and food assistance. "New Yorkers will be afraid to see a doctor," he said, per NewsNation, adding that the effect would reach beyond the families the federal government is targeting.

City Hall gave only a few hours of notice. The attorney general's office said Monday morning that the announcement involved new legal action to protect immigrant families and released nothing further, CBS New York reported.

Since taking office in January, Mamdani has worked to pull the city away from federal immigration enforcement. He signed an executive order in his first days as mayor aimed at shielding New Yorkers from aggressive enforcement, and state law already restricts how far local police may cooperate with federal agents.

Two lawsuits from the same state raise the likelihood that a federal judge will be asked to freeze the rule within days. Either case could move through the appeals system and reach the Supreme Court, amNewYork reported.