As Chief, National Guard Bureau, Blum was the senior uniformed National Guard officer, responsible for formulating, developing, and coordinating all policies, programs, and plans affecting more than half a million federalized and nonfederalized Army National Guard and Air National Guard personnel. Appointed by the U.S. president, he served as the principal adviser to the Secretary of Defense and Chief of Staff of the Army, and Chief of Staff of the Air Force on all National Guard issues. His duties also included serving as the Army's and Air Force's official channel of communication with state governors and adjutants general concerning the 54 state and territorial National Guards.