Convinced that he was destined to become President of the United States, Chandler challenged Senate Majority Leader Alben Barkley for his U.S. Senate seat in 1938. During the campaign, President Franklin D. Roosevelt came to the state to campaign for Barkley, and Chandler lost a close race. The following year, Kentucky's other senator, Marvel Mills Logan, died in office, and Chandler resigned as governor so his successor could appoint him to the vacant seat. A fiscal conservative and disciple of Virginia's Harry F. Byrd, Chandler opposed parts of Roosevelt's New Deal and openly disagreed with the president's decision to prioritize European operations in World War II over the war in the Pacific. In 1945, Chandler resigned his Senate seat to succeed the late Kenesaw Mountain Landis as commissioner of baseball. His most significant action as commissioner was the approval of Jackie Robinson's contract with the Brooklyn Dodgers, effectively integrating Major League Baseball. He also established the first pension fund for Major League players, earning him the title "the players' commissioner". Baseball owners were upset with Chandler's governance, however, and did not renew his contract in 1951.