The formation of the Progressive Party began in 1946 , after Secretary of Commerce and former Vice President Henry A. Wallace quit the Truman administration and began to publicly agitate against Truman 's policies . Calls for a third party had been growing even before Wallace , who was replaced as vice president by Franklin D. Roosevelt with the more conservative Truman at the 1944 Democratic National Convention , left the Truman Administration . One of the ironies of the contest between Wallace and Truman was that , if FDR had not replaced Wallace with Truman at the 1944 Democratic convention — at the behest of Democratic Party bosses who felt that Wallace was too liberal and too erratic — Wallace would have been President of the United States , not Truman
1944 Democratic National Convention
1944 Democratic National Convention
Progressive Party (United States, 1948)