John Hinderaker at Power Line lays the blame for an eventual loss to Obama primarily at the feet of Newt:

Nevertheless, if you are a Republican, the vibes are very bad. The presidential primary season has turned into a disaster, in my view. Mitt Romney has shown a discouraging inability to appeal to the party’s base, while the race has damaged both Romney and the party. Newt Gingrich, in particular, sacrificed the party to his own ego by launching left-wing attacks against Romney. Gingrich is gone as a Republican contender, but we will see more of him in the fall, in Obama ads. What a swan song for someone who once led the conservative movement!

This narrative has it backwards.

Newt started out positive, and tried to stay positive as Romney, his SuperPAC and his supporters in the conservative media savaged Newt in Iowa (and later Florida) with what David Limbaugh appropriately called “relentless, unmeasured scorched-earth savagery.”

None of the people engaged in Romney’s strategy of crazy cared a bit about how the attacks would hurt Newt if Newt became the nominee.  Now they complain that Newt hurt the party by attacking Romney’s Bain record; and by so doing they have conflated capitalism, free markets, and the Party with the Bain model, which will do far more damage than anything Newt ever did.

Even Peggy Noonan gets it:

The Romney campaign is better at dismantling than mantling. They’re better at taking opponents apart than building a compelling candidate of their own.

I’m not ready to write off the general election, regardless of who the nominee is.

But if you are looking for blame, look straight at the Romney campaign.