Susan Winchester was elected to the Oklahoma House of Representatives to represent District 47 in 1998 where she served until 2008. She was elected Whip for the Republican Caucus after her first term, and in 2005 became the first woman to serve as Speaker Pro Tempore, the second highest position in the House.

The Oklahoma House of Representatives is the lower house of the legislature of the U.S. state of Oklahoma. Its members introduce and vote on bills and resolutions, provide legislative oversight for state agencies, and help to craft the state's budget. The upper house of the Oklahoma Legislature is the Oklahoma Senate.