Sens. David Vitter and Chuck Grassley pressed the Justice Department Tuesday on why the State Department, under the leadership of Hillary Clinton, refused to designate Boko Haram as a terrorist organization.

“For two years, Boko Haram grew as Secretary Clinton and her Department of State refused official requests to designate Boko Haram” as a terror group, the Republican lawmakers wrote in a letter to the Attorney General Loretta Lynch on Tuesday.