There is certainly the possibility that it won't matter who the Republicans nominate--Obama will win anyway.

Latest development in this direction is McConnell's proposal on the debt ceiling crisis--which has already has resulted in an incipient civil war in the GOP.   You always want a civil war on the other side.

Now if the Left can--for once--be sensible enough to come out to vote --in 2012--for a candidate who is demonstrably not perfect, Obama will have an excellent chance.   (If the unemployment rate is down quite a bit below 9.2%.)