A similar situation may occur with the South Dakota Senate race. John Thune just narrowly squeaked by in 2002 in a red state. There's been speculation that the state's sole congresswoman, Rep. Stephanie Herseth Sandlin (D-S.D.), may challenge him. She, too, has experience at winning statewide election running as a Democrat in a fairly red state. Maybe if Castle wins in Delaware, she could win in South Dakota and this would cancel out each party's "gains."
It was actually Johnson who squeaked by in 2002 against Thune, but the point is taken. Thune defeated Daschle in 2004, and that one was close. (But Daschle was the incumbent, not Thune.)
