They make their decision by talking to each other. These are people who are interacting with each other at various conventions, and in social settings. And they are debating amongst themselves the merits of the candidates, just as there is a debate in the media and ordinary voters are debating and so forth. But they’re listening to each other in particular because they know that they have particular insights beyond what some voter who just heard about the candidate knows.

These folks might not tell you what they’re thinking while they’re still figuring it out, but one way to see it happening is through endorsements. When one of the elite actors says, I support Mitt Romney, that’s part of that conversation. And it’s a signal to other people that the private conversation about the person being for Mitt Romney is for real.

A moment ago you said voters were typically less important than party elites in this process. Of course, the decision is ultimately made by voters in primaries and caucuses. What role do endorsements play in shaping that choice?

When endorsements start to converge, voters can sense that most of or all of the party is for a particular candidate. For the most part, people who are voting in the primaries are partisan, and they listen to that party signal. We show in the book that the relationship between who has the most endorsements and who does well is strongest among partisan voters. Independent voters don’t pay much attention, but then independent voters are a smaller share of the primary electorate.

But probably the biggest way in which endorsements matter is that they’re a way for us to observe the support that’s going on behind the scenes. If the governor of a state says I’m for this candidate, it might also mean he’s going to give some advice and say in my state, these are some things you want to know. Or his staff, or people who have campaigned for him, are going to be willing to campaign for the candidate. When you show up in South Carolina to build a campaign, there are only so many people who you want to hire who know how to do that. So those people are going to have a choice of which candidate they want to run with, and they might choose the candidate who their governor supported.

I should add, we spend a lot of time in the book talking about who has the most endorsements. But the argument isn’t that whoever has the most endorsements wins. It’s that whoever the party is supporting wins, and endorsements are one way of getting at that.

There’s a passage in the book where you and your co-authors write that the 2008 Republican race was not you what would have expected; there’s even a reference to the then-impending nomination of McCain as “an embarrassment” to your argument, because he’s historically not someone the party trusted. And you wrote that come 2012, you expected the party to take steps to avoid a repeat scenario. Do you see those expectations being fulfilled now?

One thing that would have satisfied that expectation would have been changes in the rules, like the changes that the Democratic Party made after Carter’s nomination. And I don’t see that, no. That isn’t happening.

I think the one big thing that has happened is the rise of the Tea Party, especially after 2010. There are a lot of people in the Tea Party who think, we have demonstrated that the country doesn’t like Obama, we’re sure to win, we want somebody who is ideologically pure, we don’t want to nominate another moderate. And they seem like they are in a position of strength.

Meanwhile, a lot of people in the party are a little more realistic and say, well, if the economy starts to bounce back, Obama could be in a much stronger position, and we don’t want to have nominated someone who’s unelectable. So that means that a lot of people in the party leadership are at odds with a lot of other people in the party elite, the Tea Party-like folks. And they’re not sure how to play that out, so as a consequence they’re waiting. I think that’s the main explanation for why very little has happened yet.

There was just a story in Politico about how few members of Congress have endorsed anyone in the field yet. Does that fit the story that you’re telling, about how the party is waiting to make a decision?

Greg Marx is an associate editor at CJR. Follow him on Twitter @gregamarx.