A question about the US: what is the difference between a sympathiser, a registered voter, a volunteer helper, a donor, a dues-paying card-carrying member, and a member of the apparatus of the party? Which categories are important and which are not (or are even nonexistent?)

In my time, I've been a registered in

• the Democratic Party,
• no party,
• the Green Party
• the Peace and Freedom Party, and
• the Libertarian Party.

Having recorded my voter registration with the State (Nebraska, then California, now Nebraska again), I am a member of the party. My citizenship (along with my age and my lack of felony conviction) is my dues. (Some people would say that their taxes are their dues, but —unless you lose the franchise through a felony conviction for tax evasion— that's actually irrelevant.)

I'd say that I sympathise, in various ways, with the Green Party, the Libertarian Party, and the various small socialist parties (which include Peace and Freedom), although none of them really represent my views. I might also say that I sympathise with the progressive wing of the Democratic Party and (somewhat) the small-government wing of the Republican Party, even though I certainly don't sympathise with the parties themselves.

I have been both a volunteer and a donor; ironically, all of my party volunteer work was before I was 18 (voting age), so I was not a party member. For that matter, most of my donations have been to candidates of different parties. I've never donated to any party's campaign committees, but the Democrats keep asking me to, and I'm sure that they'd accept my money even though I haven't been a Democrat for years. (I even got a solicitation from the Republicans once, even though I've never been a member. Clearly these people are just using rented mailing lists, like the charity solicitations I get.)

As for member of the party apparatus …, you should talk to somebody from Iowa about that.