PHILADELPHIA (CBS) — Attorney General Jeff Sessions issued a warning to Philadelphia and other sanctuary cities this week.

Attorney General Sessions: Sanctuary Cities Must End

He says they could lose federal funding for refusing to cooperate with immigration authorities.

The attorney general also suggests the government may take back previously awarded grant money to cities that do not comply.

However, Philadelphia Mayor Jim Kenney is standing his ground.

“I took an oath to uphold the Constitution of the United States of America and that includes the Fourth Amendment,” said Kenney.

GOP-Sponsored Bill Blocks Over $1 Billion In Funding To Pennsylvania Sanctuary Cities

Kenney said, “We are not going to hold people against their will without charge. That is the Fourth Amendment of the United States Constitution. I hope Attorney General Sessions would understand what the Fourth Amendment means.”

Kenney says it is likely the courts will resolve the matter.