Better than handing the U.S. presidency over to an American-hating Marxist. It’ll be easier to shift the GOP back right than to undo the damage Obama will do (surrender in Irag, socialized medicine, Global Poverty Act, etc).
How are you going to do that? The intention for '08 was to shift back right after GWB, but that is not the result. If there was an option on the ballot to the effect that 'you are only getting this vote because I despise you a little less than the other evil', you might have a point. But, unfortunately, the GOP will read your affirmative vote as an approval of the leftward shift, and the next candidate will be even further left of McCain. It is not easy to see that political ground compromised is almost never regained.