A federal judge wrestled Thursday with whether Democratic lawmakers can sue President Donald Trump in a lawsuit one senator called the “only ball game in town” to stop the president from unconstitutionally accepting foreign state gifts without congressional approval.

Before a full courtroom Thursday morning, U.S. District Judge Emmet Sullivan of the District of Columbia heard from the U.S. Department of Justice and counsel for around 200 Democratic lawmakers suing the president on the “threshold question” of standing.