I think that depends on the nominees. If the Republicans nominate Huckabee, he’ll almost certainly take more GOP votes since many socially moderate or liberal but pro-business Republicans will abandon Huckabee for him (although without him some of these might otherwise go to Clinton or Obama).
True, but not very relevant -- in that case, the Dems have it sown up from the moment the Huckster takes the nomination, short of Hillary getting caught in bed with a 15-year-old girl or a videotape surfacing of Obama giving a jihadist address to a madrassa.