We know that Krusty, Mr. Burns, Ken Brockman , and Sideshow Bob are Republicans. And we know that Quimby is a Democrat.
Here are a list of some other Simpson Characters. Are these guys Democrat or Republican:
1. Homer
2. Marge
3. Moe
4. Skinner
5. Comic Book Guy
6. Otto
7. Flanders
8. Rev. LoveJoy
9. Apu
10. Snake
11. Mrs. Krapabble
12. Lenny
13. Lionel Hutz
14. Grandpa
15. Cletus
Homer- Republican, though an very apethetic one
Marge-Democrat
Moe-Democrat, being a first generation immigrant
Skinner-Democrat. Too afriad to make a choice, but Edna convinces him and he has to kow tow to the teacher unions
Comic Book Guy-Republican, small business owner
Otto-Democrat, he'd want to stick it to the man
Flanders-very Republican, part of religous right
Apu-Republican, also small business owner and first genreation Indians are usually GOP
Mrs. Krabaple-Democrat, for obvious reasons
Lenny-Republican because he disagrees with Carl
Carl-Democrat because he disagrees with Lenny
Lionel Hutz-Democrat, because he's with the ambulance chasers
Grandpa-Democrat, because he's pissed with Bush's Social Security plan
Cletus-Republican, because his hillbilly constituency
Keep in mind, these are vast generalizations.