While serving as a senator from Missouri , Truman rose to national prominence as the leader of the Truman Committee , which investigated wasteful and inefficient practices in wartime production during World War II . As the war continued , President Franklin D. Roosevelt sought re-election in the 1944 presidential election . Roosevelt personally favored either incumbent Vice President Henry A. Wallace or James F. Byrnes as his running mate in 1944 . However , Wallace was unpopular among conservatives in the Democratic Party , while Byrnes was opposed by liberals and many Catholics . At the behest of party leaders , Roosevelt agreed to run with Truman , who was acceptable to all factions of the party , and Truman was nominated for vice president at the 1944 Democratic National Convention
1944 Democratic National Convention
1944 Democratic National Convention
Presidency of Harry S. Truman