Byron York notes that Rick Santorum isn’t being taken seriously as the leading candidate for 2016:

And yet now, no one — no one — is suggesting Santorum will be the frontrunner in 2016, should he choose to run. As far as the political handicapping goes, Santorum’s 2012 victories don’t seem to count for much.

York offers some explanations for why this is so, focusing mostly on Santorum’s social conservatism. It’s certainly true that Republican donors tend to see Santorum primarily as a social conservative, and a very vocal one at that, and most of them aren’t interested in backing that kind of candidate. Many of them don’t agree with Santorum on these issues, and even some that do see Santorum’s attention to these issues as a general election weakness. That’s an important factor that will severely limit Santorum’s fundraising if he wants to run again, but it doesn’t tell the whole story. York presents Santorum’s message on economic issues as one of the strengths of the campaign, and to some extent it was, but what goes unmentioned here is how allergic many in the GOP are to anything that sounds like economic populism. His voting record is littered with all of the major blunders of the Bush years, so he can’t very credibly pose as a champion of limited government, and he has been denouncing libertarians for the better part of a decade. Santorum also comes across as abrasive, and when he speaks it usually feels as if he is lecturing and dictating to the audience rather than trying to appeal to them. If you wanted to invent a politician who could alienate several different parts of the Republican coalition all at once, you would design someone like Santorum.

Probably Santorum’s biggest vulnerability is something that York only mentions in passing: his extremely aggressive foreign policy views. It’s not just that Santorum is a vocal hawk, which by itself wouldn’t be a problem in the contest for the nomination, but that he is fanatically hawkish in a party that is moving gradually in the other direction. He specializes in threat inflation and alarmism, which he takes to comical extremes, and was so uncompromising as an Iraq war supporter that he voted against Gates’ confirmation as Secretary of Defense under Bush because he thought Gates was not hawkish enough. That makes his foreign policy record a serious liability in a general election, but it is also an inviting target for any Republican rivals that want to position themselves as hawkish-but-not-crazy.