John Huntsman is a moderate candidate that will have significant crossover support. Maybe if he chooses Buchanan as his running mate (home state advantage obviously) they could win some precincts and make Clinton spend money to defend the district.
I think this ticket could win 700 electoral votes.
Add the Moon Colony's 245 electoral votes (voted 99% for Huntsman because of Newt Gingrich's endorsement) and you get:
Huntsman (R-UT)/Buchanan (R-DC): 700 Electoral Votes
Clinton (D-NY)/Castro (D-TX): 83 Electoral Votes