President Trump has escalated his administration’s conflict with local governments regarding immigration enforcement, saying on Wednesday that federal funding will be halted for states housing “sanctuary cities” beginning next month.

The president used social media to deliver the edict, targeting jurisdictions that limit cooperation with federal immigration authorities.

“Effective February first, no more payments will be made by the federal government to states for their corrupt criminal protection centers known as sanctuary cities,” Mr. Trump wrote in a post on Truth Social. “ALL THEY DO IS BREED CRIME AND VIOLENCE! If States want them, they will have to pay for them! MAKE AMERICA GREAT AGAIN!!!”

The announcement expands on rhetoric from a speech delivered Tuesday at the Detroit Economic Club, where Mr. Trump criticized these jurisdictions for refusing to align with federal deportation efforts.

“Starting February 1, 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 his speech. “So we’re not making any payment to anybody that supports sanctuary cities.”

While the President did not immediately specify which federal revenue streams would be frozen, he hinted at the scale of the financial penalty when questioned by reporters in Washington. “You’ll see,” he said regarding the specific funds involved. “It’ll be significant.”

This directive follows an executive order signed in April, which instructed Attorney General Pam Bondi and Homeland Security Secretary Kristi Noem to “identify appropriate Federal funds to sanctuary jurisdictions, including grants and contracts, for suspension or termination, as appropriate.”

However, the administration faces significant legal hurdles to Mr. Trump’s threats. Similar efforts during his first term in 2017 were struck down by the courts. Furthermore, a federal judge in California, U.S. District Judge William Orrick, recently extended a preliminary injunction blocking the administration from withholding funds from more than 30 jurisdictions.

Under the U.S. Constitution and federal law, the president cannot unilaterally cut off funding to a state that has already been appropriated by Congress. While the executive branch administers the budget, the “power of the purse” belongs strictly to the legislative branch.

Despite these legal blocks, the administration has ramped up pressure through other avenues. Ms. Bondi recently sent noncompliance letters to 32 jurisdictions, including California, New York, Illinois, and Connecticut.

Simultaneously, federal agencies have begun targeting specific state funding streams. The Centers for Medicare and Medicaid Services recently informed Minnesota officials of an intent to withhold $515 million quarterly from Medicaid programs deemed “high risk,” while the Department of Agriculture has warned states refusing to provide data on SNAP recipients that they may lose administrative funds.