I still think the concept is excellent. However, I feel like it could do with being 'Werewolved up' - you need real, out-and-out bad guys for these kind of games. So next time, I'd suggest that there's a secret Space-Nazi party. Okay, maybe named to be more in keeping with the theme, but you get the idea. Basically, everyone is part of a given party, but there's also an evil 5th column within the ranks, assassinating members of parliament in order to stage a coup.
The mechanics would be set up so that this evil foreign influence had to be defeated, but the competing parties have to work together to do it. A party would win if and only if the 5th columnists have been defeated, and they hold a majority in parliament. The 5th columnists win if they kill enough MPs to be able to stage a coup and dissolve Parliament. Arresting the 5th Columnists would require cross-party support, but would also inevitably involve some MPs voting to arrest members of their own party. Breaking the party line and voting against a fellow party-member might win you trust, but possibly suspicion.
Some of the voting mechanisms might have to be trimmed in order to accommodate the new stuff, but I'm not sure which or how. I might have a think about this and suggest some ideas, because I really like the concept.
Oh, and sorry I've been so inactive.