Question: Al Franken's 2008 United States Senate election opponent had previously been a member of which political party before becoming a Republican?
Sentence (from "United States Senate election in Minnesota, 2008"): After a legal battle lasting over eight months, Al Franken from the Democratic-Farmer-Labor Party (DFL) defeated Republican incumbent Norm Coleman in one of the closest elections in the history of the Senate.
Relevant evidence: Yes