I did a post over at PP a couple of days ago about Christie and personality, pointing out that personality -- whether people actually liked the candidate -- can matter quite a bit in nomination contests, but is mostly unimportant in general elections.
It's worth elaborating on that just a bit, because it turns out the way that personality works is actually a bit complicated.
I can think of at least three ways that personality matters in nomination contests. In each case, I'm using "like" here to refer to personality, not issues or governing abilities or any of the other reasons someone might like a candidate.
1. It probably matters to some extent whether party actors like candidates personally. It's surely not as important as agreeing on issues, at least not issues of importance to any particular party actor, but it's probably not irrelevant, either. Or, to put it bluntly, it probably matters whether party actors like the candidates.
A couple of things about this...the universe of "party actors" is pretty large. Even just politicians...there are an enormous number of politicians in the US. But of course there are a lot more activists, and there are plenty of campaign and governing professionals, and leaders of party-aligned interest groups, and formal party officials and staff. It all adds up to a lot of people. The nature of it is, however, that each of them knows a lot of others within the "expanded party" network, and while it's large, it's still nothing like the millions in the overall electorate. My guess is that candidates' personal reputations are well-established, at least by the end of the invisible primary, among party actors, with much of that second- and third-hand in addition to whatever is being reported in the mass media.
2. It probably matters what party actors think about whether voters, both primary and general election voters, will like candidates. This is almost completely separate from the whether they themselves like the candidates. It's also pretty much separate from whether voters will actually like the candidates or not. And all the qualifiers about the universe of party actors apply; reputation matters.
3. It probably matters what voters think of the candidates as people. We can go way overboard on this: voter impressions of candidates are very much filtered through elite opinion leaders and, generally, how the candidates are presented in the mass media. And in many cases, it doesn't matter because many candidacies don't survive to the point at which voters get engaged. Still, there's no reason to believe that the primaries and caucuses do absolutely nothing except to ratify the decisions of party actors, at least not in every case.
I suppose there might be more 2nd- and 3rd-order possibilities as well; for example, primary voters who support a candidate based on their perceptions of how likable that candidate will be for swing voters in November. But I think those three capture the bulk of it. The key, again, is that these are all actually separate things, all more or less independent of each other.