William Borah was an American politician who served as a United States Senator from Idaho from 1907 to 1940. He was a member of the Republican Party and became known for his strong advocacy of progressive reforms and his opposition to the New Deal policies of President Franklin D. Roosevelt. Borah was also a prominent figure in foreign affairs, particularly during the interwar period. He was a vocal critic of the League of Nations and played a significant role in shaping U.S. foreign policy, emphasizing isolationism and non-interventionism during his tenure in the Senate.