John McCain’s troubles with conservatives have him in a whole lot of trouble for reelection next year. Even among Republican primary voters just 41% approve of the job he’s doing to 50% who disapprove. Only 37% of primary voters say they generally support him for renomination, compared to 51% who say they would prefer someone ‘more conservative.’

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.

If he survives to the general McCain has leads of 4 to 6 points against the Democrats we tested again him- he’s up 40/36 on Fred DuVal, 40/34 on Richard Carmona, and 42/36 on both Ann Kirkpatrick and Kyrsten Sinema. Those numbers may be misleadingly close though- the undecideds in each of those match ups are strongly Republican leaning and voted for Mitt Romney by more than 20 points in 2012. They’re mostly the conservatives unhappy with McCain and usually at the end of the day those people will vote Republican before they will leave it blank and certainly before they vote Democratic, even if they don’t care for McCain. The 17-19% of the Democratic vote McCain attracts in a general election makes him difficult to defeat if he gets that far.

If McCain does lose renomination or eventually decides not to run again all bets are off though. We tested Richard Carmona, as the 2012 nominee, in hypothetical contests against all the Republicans we looked at against McCain in the primary. Salmon, at 43/35, is the only one who leads Carmona. Carmona and Schweikert are tied at 39, and Carmona leads both Ward (39/36) and Jones (42/36) by modest margins.

In a lot of ways this is reminiscent of the 2012 Senate race in Indiana. Richard Lugar- like McCain- had enough popularity across party lines that he was going to be pretty safe if he got into a general election. But when conservatives rooted him out of office in the primary and Democrats had a solid candidate lined up, the Democrats picked up a surprising victory. It’s unclear who will challenge McCain in the primary and what Democrat might sign up for the general but at this early stage the conditions appear somewhat Indiana-like.

Full results here