When World War II focused President Franklin D. Roosevelt 's attention on foreign affairs , Barkley gained influence over the administration 's domestic agenda . He resigned as floor leader after Roosevelt ignored his advice and vetoed the Revenue Act of 1943 . The veto was overridden and the Democratic caucus supported and unanimously re-elected Barkley to the position of Majority Leader . Barkley had a good working relationship with Harry S. Truman , who ascended to the presidency after Roosevelt 's death in 1945 . With Truman 's popularity waning entering the 1948 Democratic National Convention , Barkley gave a keynote address that energized the delegates . Truman selected him as his running mate for the upcoming election and the Democratic ticket scored an upset victory . Barkley took an active role in the Truman administration , acting as its primary spokesman , especially after the Korean War necessitated the majority of Truman 's attention . When Truman announced that he would not seek re-election in 1952 , Barkley began organizing a presidential campaign , but labor leaders refused to endorse his candidacy because of his age , and he withdrew from the race . He retired but was coaxed back into public life , defeating incumbent Republican Senator John Sherman Cooper in 1954 . Barkley died of a heart attack while giving a speech at the Washington and Lee Mock Convention on April 30 , 1956
1948 Democratic National Convention
1948 Democratic National Convention
Alben W. Barkley