President Trump this week threatened to cut off federal funding to any states where local governments oppose his administration's immigration policies.

It's not the first time the president has threatened to halt federal funding for so-called sanctuary cities, but insiders said unlike previous efforts, this one might stick.

"Starting February 1st, we're not making any payments to sanctuary cities or states having sanctuary cities, because they do everything possible to protect criminals at the expense of American citizens and it breeds fraud and crime and all of the other problems that come," Mr. Trump said in a speech Tuesday at the Detroit Economic Club. "So we're not making any payment to anybody that supports sanctuary cities."

The president has made similar threats before to punish sanctuary cities, which he claims make the country less safe.

Chicago city officials have said the president's latest threats target funding for public health, transportation, and public safety. 

In August, a federal judge blocked the Trump administration from cutting off federal funding for dozens of sanctuary cities and counties, including Chicago. The judge had previously ruled that it was unconstitutional for President Trump to freeze funding for local governments that limit their cooperation with federal immigration enforcement efforts.

Mayor Brandon Johnson predicted a similar fate for the president's latest threat.

"I'm confident that, as the courts have done before, rule in our favor that he is working outside the Constitution," he said.

But others were not so fast to dismiss the president's threat.

"If they take away the same kind of money they took away in the summer, the mayor is right. The city will win. But if it's another kind of money, who knows?" said Northwestern Pritzker School of Law professor Nadav Shoked.

Shoked said the Trump administration is getting savvier – picking specific grant dollars that have the loosest rules, giving the White House an advantage in controlling such funds.

"A lot of these grants are very, very open-ended. The Department of Transportation gets to pick whatever project it wants, because it just gets to define what's a good project, and then they can just decide we're not funding projects in Chicago, and nothing stops them from doing that,"

That effort has already begun.

Ald. Rossana Rodriguez (33rd) said that, just one day after the president's announcement, clinics in her ward have learned federal funding has already stopped.

"This is a huge, huge hit," she said in a video posted on her Facebook page. "We know that a lot of people will be hurt, and some will die without these life-saving services."

"It's not inconceivable that they' re much pickier this time in picking what money they're going to keep away from the city, in a way they pick specific funds that they're allowed to do it," Shoked said.

Experts believe the cities being targeted by the Trump administration will likely band together again to mount a similar court challenge, which could be trickier as the administration has learned from past failures.