Mayor Johnson was asked​ by the House Oversight Committee to testify on Capitol Hill next month about Chicago's sanctuary city status — along with other big city mayors.

The mayors of Chicago, Boston, Denver and New York were also asked to hand over all documents and communications related to their cities' sanctuary status, including those between each city, non-governmental organizations and state officials.

If Mayor Brandon Johnson refuses to appear as requested, it could open a new front in the ongoing battle with the GOP-controlled U.S House and the Trump administration, which is attempting to strip self-proclaimed sanctuary cities of all federal funding.