Democratic mayors of major U.S. cities that have long had cool relationships with federal immigration officials say they’ll do all they can to protect residents from deportation, despite President-elect Donald Trump’s vows to withhold potentially millions of dollars in taxpayer money if they don’t cooperate.

New York’s Bill de Blasio, Chicago’s Rahm Emanuel and Seattle’s Ed Murray are among those in “sanctuary cities” who have tried to soothe immigrant populations worried about Trump’s agenda.

“Seattle has always been a welcoming city,” Murray said Monday. “The last thing I want is for us to start turning on our neighbors.”

In Providence, Rhode Island, Mayor Jorge Elorza, the son of Guatemalan immigrants, said he’d continue a longstanding city policy of refusing to hold people charged with civil infractions for federal immigration officials, and Newark’s Ras Baraka echoed that, calling Trump’s rhetoric on immigration “scary.”

During the campaign, Trump gave an immigration speech in which he promised to “end the sanctuary cities” and said those “that refuse to cooperate with federal authorities will not receive taxpayer dollars.” He blamed such policies for “so many needless deaths.”

Trump didn’t elaborate further on his plans for cracking down on the cities, and in a “60 Minutes” interview broadcast Sunday, he said his administration’s immediate priority will be on deporting criminals and securing the border.

But significant questions — and unease — remain concerning his approach to sanctuary cities.

There’s no legal definition of the term, which is opposed by some immigration advocates, who say it doesn’t reflect that people can still be deported. It generally refers to jurisdictions that don’t to cooperate with U.S. Immigration and Customs Enforcement. That can mean, for example, they don’t notify immigration officials when an undocumented immigrant is about to be released from custody.

Some cities, like San Francisco, have long declared themselves safe havens for immigrants, issuing local ID cards to allow them to access government or other services. It’s also been used to refer to cities that bar employees, including police, from inquiring about a person’s immigration status, on the grounds that crime victims and witnesses might be less likely to talk to investigators if they’re worried about being deported.

“We don’t want anybody to be afraid to talk to us,” said Sheriff John Urquhart in Washington’s King County, which includes Seattle.

Since states and cities can’t be required to enforce federal law — and there’s no federal law requiring police to ask about a person’s immigration status — it’s likely that any Trump effort to crack down on sanctuary cities would focus on those that refuse to comply with ICE requests, said Roy Beck, chief executive of NumbersUSA, which wants to see immigration levels reduced.

It’s also unclear what money Trump might pull from the cities. The U.S. Supreme Court has held that for Congress to impose conditions on the receipt of federal money by the states, the conditions must be reasonably related to the purpose of the money. For example, the feds threatened to withhold highway funds from any state that failed to adopt a 0.08 blood-alcohol limit: Both the limit and the highway funding were related to road safety.

“If the funding is for improving childhood education, it’s hard to say that’s reasonably related to local law enforcement cooperation with deportations,” said Mary Fan, a University of Washington Law School professor.

That said, the U.S. Justice Department’s inspector general looked at some jurisdictions with sanctuary policies earlier this year and concluded some appear to violate a federal law that says state and local governments may not prohibit or restrict officials from sharing information about a person’s immigration status with federal immigration officials. Having such policies could jeopardize millions of dollars in DOJ grant money the jurisdictions receive, the IG memo said.

According to the Center for Immigration Studies, which also calls for lower immigration levels, about 300 jurisdictions around the country have sanctuary-like policies.

“The result is people who should be deported, who have come to the attention of police because of crime, are released back into the community,” said the group’s director of policy studies, Jessica Vaughan.

Exhibit A for supporters of a crackdown on sanctuary cities is the fatal shooting of Kate Steinle in 2015, on a San Francisco pier by a man who had been previously deported and who was released by local law enforcement.

But pro-immigration advocates say they’re worried that Trump’s plans will wind up deporting much more than violent criminals and they’re gearing up for a fight, in the sanctuary cities and beyond.

“These cities have reaffirmed they’re going to respect the dignity of all their residents,” said Matt Adams, legal director at the Seattle-based Northwest Immigrant Rights Project. “What they’re saying is, ‘We’re not going to use our resources to separate families, to deport children, to tear communities apart.'”

(AP)