Dozens of people marched from Times Square to Columbus Circle on Saturday, calling for the release of Palestinian activist Mahmoud Khalil, a Columbia University graduate student and green card holder.

NEW YORK (AP) — Demonstrators from a Jewish group filled the lobby of Trump Tower on Thursday to denounce the immigration arrest of a Columbia University activist who helped lead student protests on the Manhattan campus against Israel’s war in Gaza.

The university sanctions demonstrators involved in pro-Palestinian protests last spring while the arrest of organizer Mahmoud Khalil has become a flashpoint on the rights of legal U.S. residents and free speech.