The letters, sent from Chairman Trey Gowdy (R-S.C.) to White House counsel Don McGahn and the leaders of two dozen federal departments and agencies, demand answers to inquiries about the use of nonofficial email and other messaging accounts to conduct official business. Rep. Elijah E. Cummings (D-Md.), the ranking Democrat on the panel, also joined the request.

The letters represent some of the most aggressive oversight of the Trump administration from Gowdy, who took over the reins of the Oversight Committee in June after Chairman Jason Chaffetz (R-Utah) announced plans to resign his congressional seat. They come after the Republicans on the committee repeatedly questioned Democrat Hillary Clinton’s use of private email, hosted on a personal server, during her tenure as secretary of state.