Bearing in mind that TPM is meant to be a small game, and I don't and wouldn't want it to lose that "small game" feel:
Suggestion #1
As a big fan of Gal Civ II: What about "Mega events" in TPM 2012? Turn on or off as the player prefers, but having an event or two shake up the political landscape and voters reactions would make candidates have to deal or downplay their stands on an issue which usually doesn't get much play (the quirkier ones at the bottom).
Suggestion #2:
Two or three more (possibly fictional) maps to fight over. The challenge of the Drengin, for example, is that the map is different, with different electoral votes, issues and strategies. What about a "fantasy world" map in the same vein (perhaps borrowing from the fantasy game Stardock is thinking about doing)?
Again, I don't want TPM to bloat too large in price and features--but a couple of improvements would make it even more fun.
And now if you excuse me, I have to go teach Jimmy Carter a lesson in Drengin politics...