How do I deal with my new roomate without kicking his ***...?

I grew up with this guy so I've known him for a long time. Recently I just moved to the town that he lives in and he's really helping me out by letting me stay with him til I find a place which I really appreciate. Anyway, he's recently turned into a conservative republican an honestly I think it's because his boss is one, he used to be a huge liberal. He's messy, and he's a real downer. He's so bitter and negative about everything. Whatever we're doing and it doesn't matter what we're doing he'll point out the negative in everything and he'll somehow involve his political views into it. He thinks he's smarter than everyone that's not republican and that his views are right and everyone else is wrong. And I don't even think he fits the conservative group. He's poor, addicted to weed, messy, refuses to pay bills and many other things. I hardly have room to explain myself fully but I can't stand his negativity and self righteousness anymore. Help me.