South Carolina Democratic Party executive director Amanda Loveday confirmed to TheWrap Friday that Colbert-Busch is expected to file Tuesday to run as a Democrat in a special election.
While her brother's fame may help her, his SuperPAC probably won't: The comedian announced last month that it would donate its $773,704.83 to charities supporting Hurricane Sandy relief, wounded veterans, and clean-government groups. Colbert has previously mounted two mock runs for president.
Among Colbert-Busch's opponents is Sanford, who famously disappeared for a week in 2009. Reporters were told that he was hiking the Appalachian Trail, but it soon emerged that he was actually carrying on an affair.
Colbert-Busch is running in a challenging district for Democrats: Republican Tim Scott won it by 62 percent in November, but was named to take Jim DeMint's U.S. Senate seat last month after DeMint announced he would step down.
The director of business development for Clemson University's Restoration Institute, Colbert-Busch has had a life marked by tragedy. Her father and two of their brothers were killed in a plane crash in 1974.
Nineteen at the time, she dropped out of school at the University of South Carolina to live with her mother and the then-10-year-old Stephen, according to a profile in The Post and Courier newspaper. She began dating and eventually married a man who later ended up on "America's Most Wanted" in connection to a securities fraud case. She has since remarried.
The newspaper said she was also sitting in a building across from the World Trade Center on Sept. 11, 2001, as hijacked planes slammed into the twin towers.