Henry A. Wallace
Wallace had been Franklin D. Roosevelt's Vice President and a liberal leaning politician. He was replaced as Roosevelt's running mate in the 1944 elections by the pragmatic Harry S Truman, who when the duly elected Roosevelt died 82 days later became President and in various decisions which included using the atomic bomb against Japan, started and stoked a long-lasting Cold War with the Soviet Union. Wallace ran in 1948 as the nominee of the Progressive Party which he helped form after earlier leaving Truman's government, but was beaten by Truman.