Support for political parties is interesting, though. I assume there are some people (party members and activists) who are pretty much in agreement with all policies (or at least claim to be), or can see good arguments for a particular policy and feel like they should defend the party stance. However, I would think most people, including many party members, have a general alignment with the ethos of a party but don't necessarily agree with everything they do... members may at least be able to influence policy, but I assume "habitual voters" may not even be aware of detailed policy on many things, but are happy to vote for the party "because they always have" and they agree with their overarching aims. Of course, other voters may switch alliegance based on all sorts... good (or bad!) policies on a pet subject, good (or bad) candidates, really not wanting another party to win so voting tactically and so on and so on...
I saw a survey a couple of years ago that I can't find again (though I'm aware that without it what I'm going to say comes in the 87% of statistics are made up on the spot category). But it looked at how personally members of different parties took a criticism of their party/ party leader/ policies etc. The SNP members were way top of how personally they felt about criticism of the party. I can kind of see why that would be in terms of independence almost being an identity, but it was really noticeable how different the SNP was compared to eg labour and tory etc, who were much more similar to each other, and generally didn't have the same personal connection with the party and could "accept" criticism to a greater extent without seeing it as a personal attack. I'm going to keep looking, because it was interesting, but it was a while ago I saw it!