Immigration law, the mayors said, is a federal responsibility, and the attempt to put that responsibility on local law enforcement makes communities distrust the police and others they may need to call for help. Trump’s crackdown, the mayors said, has terrified immigrants, many of them in the U.S. legally.

Mayor Brandon Johnson argued that Chicago’s policies made the city safer and allowed residents to help the police solve crimes without fear of deportation.

The Democratic mayors of Boston, Chicago, Denver and New York City defended their cities’ policies amid a Republican-led Congressional investigation.