Elf Sternberg

The conclusion I've reached is that its just a symptom of the system: if someone cares enough about politics to make it a big part of their life (i.e. a party partisan), odds are they aren't a moderate, since the latter have other priorities than volunteering long hours to help a political candidate or cause.

The candidates also know they have to hew to certain positions or the party partisans will get someone to replace them: when was the last time a major Democratic candidate was able to state anything but 100% dedication to the right to choose, for example? Fortunately the moderate middle gets their opportunity to be heard in the general elections, which prevents things from tipping too far either way, but the parties are run by the "true believers" and that's not going to change.