Finn said:
And I mean this question to be purely hypothetical.
It's a fair question. Party is a slightly different beast, because at that point you're dealing with how the candidate interacts with the rest of Congress or the House. Even if I were to like a Democrat better than McCain (like, say, Hillary Clinton), I would have to keep in mind that she would have had to barter and bargain
heavily with Pelosi and Reid in order to govern - which may (would, in this case) undermine why I would prefer her in the first place.
Though I would agree less with McCain, though, on key issues, he would have to work
as a Republican and thus get the support of his party when and where it's needed. Certainly the Democrats have proven that bipartisanship is nothing more than lip-service these days.
So, that's where 'voting party' may come in. You're less voting the candidate, and voting the ideals that the overall party supposedly stands for (which is admittedly problematic), knowing that all the candidates, in theory, are pushing to make the agenda happen. (It's the Primaries where the candidates should be sorted out, in these cases.)
Edit: And on an unrelated note... post #500