Johnson won election to the Senate in 1916, becoming a leader of the chamber's Progressive Republicans. He made his biggest mark in the Senate as an early voice for isolationism, opposing U.S. entry into World War I and U.S. participation in the League of Nations. After World War I, he helped enact the Immigration Act of 1924, which severely restricted immigration from East Asian countries, Southern Europe, and Eastern Europe through the use of racial quotas. He unsuccessfully sought the Republican presidential nomination in 1920 and 1924 and supported Democratic nominee Franklin D. Roosevelt in the 1932 presidential election. While Johnson initially supported many of Roosevelt's New Deal programs, he became more hostile to FDR after the latter was re-elected in 1936. He remained in the Senate until his death in 1945.