It’s his struggles on the right that have McCain imperiled. He gets narrowly positive reviews from both ‘somewhat conservative’ (51/37) and moderate (50/44) Republicans. But among those who identify themselves as ‘very conservative,’ just 21% approve of the job McCain is doing to 71% who disapprove. 83% of voters within that group say they would be more inclined to vote for an alternative on McCain’s right next year compared to only 11% who actually say they would vote for McCain.

The good news for McCain is that he does lead all the prospective primary challengers we tested against him in head to head match ups, although some of them would clearly start out as toss ups. McCain leads David Schweikert 40/39, Matt Salmon 42/40, Kelli Ward 44/31, and Christine Jones 48/27. Those tepid leads may be largely a function of the limited name recognition of his potential opponents though. Salmon has 52% name recognition, Schweikert 47%, Jones 44%, and Ward just 27%. Salmon (a +28 favorability at 40/12) and Schweikert (a +15 favorability at 31/16) are both far more popular than McCain among the voters who are familiar with them.

McCain will have an immense war chest that may scare off his stronger potential challengers- but it’s clear that the distrust he faces from conservatives makes him at least hypothetically vulnerable to a foe on the right.