Boston Mayor Michelle Wu has been asked to testify at a Congressional hearing as part of a federal investigation into sanctuary cities.

Boston Mayor Michelle Wu says her administration feels “very strongly that we’re on solid legal ground” in being a sanctuary city and is still reviewing a letter it received from Congress on getting called to testify on such policies.

On Monday, the House Committee on Oversight and Government Reform opened a probe into so-called sanctuary cities for immigrants and has requested testimony from Boston Mayor Michelle Wu.