What a great subject!
I think Jerry might be an undecided voter, he'd certainly have voted Clinton and Gore, but might be considering voting Bush this time on issues of defense. If he were to ever identify with Republicans he'd be a 'liberal Republican' and would have voted for Guiliani.
Kramer certainly isn't a Republican, he could be anything really, I kinda doubt he's a libertarian because ... because! (they're an irrelevant party to be perfectly honest.) He might possibly be a Nader (and possibly previously Perot) voter just because of his wackiness causing him to support the third party candidate + he reads the 'independant media'. More likely than all he wouldn't vote.
To cheer you libertarians up: George Costanza is a pretty selfish guy, therefore libertarian seems like a natural choice. Haha just kidding ... just the fact that he lives in Manhatten makes him a likely democrat.
Jerry's parents: Jewish, Floridianian retirees = Democrat (although given those polling machines they might've accidentally voted for Buchanan in 2000).
George's parents: In one episode Frank says that because he wasn't born in the USA he can never become president, which caused him to never have any interest in politics "I don't want them and they don't want me!" - a definite non-voter. I haven't a clue who Estelle would vote for... possibly Georgie
Can't think of others atm...
