Senate Judiciary Committee Chairman Chuck Grassley is stepping up congressional oversight over unscrupulous visa programs that lure foreign students and lead to an excess of visa overstays. He’s also calling for new restrictions on foreign students who apply to U.S. school programs that allow them to work in the United States.

Grassley, R-Iowa, sent a letter Monday to Homeland Security Secretary Kirstjen Nielsen requesting information about the Student and Exchange Visitor Program, and how the department enforces regulations “that prevent spurious businesses from posing as institutions of higher learning.”