A new Rasmussen Reports survey in Delaware shows that Rep. Mike Castle (R-DE) would defeat Attorney General Beau Biden (D) by five points in a U.S. Senate match up, 47% to 42%.
Castle is expected to either run for Senate or retire next year.
Against the only declared GOP candidate for the race, Christine O'Donnell (R), Biden would win by nine points, 49% to 40%.