While some Democrats had opposed Roosevelt 's nomination in 1940 , the president faced little difficulty in securing his re-nomination at the 1944 Democratic National Convention . Roosevelt made it clear before the convention that he was seeking another term , and on the lone presidential ballot of the convention Roosevelt won the vast majority of delegates , although a minority of Southern Democrats voted for Harry F. Byrd . Party leaders prevailed upon Roosevelt to drop Vice President Wallace from the ticket , believing him to be an electoral liability and a poor potential successor in case of Roosevelt 's death . Roosevelt preferred Byrnes as Wallace 's replacement but was convinced to support Senator Harry S. Truman of Missouri , who had earned renown for his investigation of war production inefficiency and was acceptable to the various factions of the party . On the second vice presidential ballot of the convention , Truman defeated Wallace to win the nomination
1944 Democratic National Convention
1944 Democratic National Convention
Franklin D. Roosevelt