Top Republican senators are pushing the State Department to grant an interview with the agency’s chief information officer in the hopes that he can shed some light on the activities of Bryan Pagliano, a former aide to Hillary Clinton who has invoked his Fifth Amendment right to decline lawmakers’ questions.

Sens. Charles Grassley and Ron Johnson requested Steven Taylor, the agency’s top IT official, sit for a closed-door interview about Pagliano and his role in administering the Clinton email network, according to a report by Politico.