Harry Truman Campaign Buttons. Welcome to the Harry S. Truman campaign buttons section on campaignbuttons-etc. Following the death of President Franklin D. Roosevelt on April 12, 1945, Harry S. Truman was sworn in as the 33rd President of the United States. President Truman oversaw the successful conclusion of World War II and then in 1948 was elected to his own term over New York Governor Tom Dewey. Pictured here are Harry Truman campaign buttons from his historic campaign of 1948 as well as his January 20, 1949 presidential inauguration.