Truman had ascended to the presidency in April 1945 after the death of Franklin D. Roosevelt. Defeating attempts to drop him from the ticket, Truman won the presidential nomination at the 1948 Democratic National Convention. The Democratic convention's civil rights plank caused a walk-out by several Southern delegates, who launched a third-party "Dixiecrat" ticket led by Governor Strom Thurmond of South Carolina. The Dixiecrats hoped to win enough electoral votes to force a contingent election in the House of Representatives, where they could extract concessions from either Dewey or Truman in exchange for their support. Truman also faced a challenge from his party in the form of former Vice President Henry A. Wallace, who launched the Progressive Party and challenged Truman's confrontational Cold War policies. Dewey, who was the leader of his party's liberal eastern wing and had been the 1944 Republican presidential nominee, defeated Senator Robert A. Taft and other challengers at the 1948 Republican National Convention.