If anything's constant in American political life, it's the stable two-party system, jostled occasionally by third-party presidential challengers such as Ross Perot in 1992 and 1996, or Theodore Roosevelt in 1912. In 1948, the first post-World-War-II presidential election year, Republicans ran against three Democratic Party factions: Harry Truman's pro-New Deal, anti-communist majority wing , a Southern-based segregationist offshoot led by Strom Thurmond and pro-Communist bolters headed by former Vice President Henry Wallace.