How about one for Seth Masket, for an excellent explanation of just what it was that prevented the pretenders from winning the GOP nomination in 2012. See also John Sides, but Seth is focused more on this part of it.
No, it wasn't the voters. It was -- you guessed it -- the Republican Party. Well, collectively, it was; individually, it was lots and lots of individual Republican party actors.
What's tricky about all of this is that there's no fixed formula to tell us how important activists are compared with, say, campaign professionals. Or how important particular party-aligned interest groups are, or how important the party-aligned press is, or how important party politicians are.
Or, within that: how important is Rush Limbaugh compared with, I don't know, Glenn Beck? How important is this governor compared with that Senator, or this Iowa-based activist motivated by home schooling compared with that South Carolina based activist primarily interested in immigration?
My sense of all this is that we're still early in the process of understanding all of this, especially since it's (at least potentially) shifting all the time. To the extent that a party is either strictly hierarchical or extremely monolithic, then it's fairly easy, but the more a party differs internally and is internally democratic, the more it's going to be very hard for anyone -- insider or outsider -- to figure out exactly who has how much of a say.
But even if it's hard to study, that's where the action is. And sometimes it's easy; the big whopping zilch in terms of endorsements that several of the candidates put together in 2012, even after they were able post impressive-looking wins in primaries, was an easy tip-off.
At any rate, the key to understanding all of this is knowing where to look. And most of the time, that means party actors, not voters.
Also: nice catch!