If either ends up with the nomination, I'm voting third-party.
This is, of course, what the Democrats are counting on.
That the social cons stay at home? No way. Especially if Hillary is your nominee. We don't want to sell out, but we'd rather sell out with a Giuliani/Romney than risk a President Clinton, redux. This is evidenced already by the myriad conservative scions selling out and endorsing Giuliani and Romney in spite of their shoddy social con records. The more principled of us may boycott or vote third party, but not enough to help out the Dems. GOP won't let that happen. Watch for the new wedge issue, whatever it is (immigration, eh, maybe...not sure social cons care as much -- plus, Huckabee's social gospel populism takes a more conciliatory approach towards the immigration prob).