Against the GOP, Obama is the best bet in the Zogby poll:

His margins of advantage range from a 4 percent edge over Arizona Sen. John McCain and a 5 percent edge over Arkansas’ Mike Huckabee to an 18 percentage point lead over Mitt Romney of Massachusetts, the survey shows. Against New York’s Rudy Giuliani he leads by 9%, and against Fred Thompson of Tennessee he holds a 16 point edge.

Clinton loses to Huckabee, Giuliani and McCain. Perhaps just as interesting: Huckabee and McCain are the most viable general election candidates.