So you have Archie Bunker for a FIL, eh?
That must be fun. I always loved that show but "Meathead" would always come back at Archie and you can tell the old man just loved it.
Plus it made for good television.
Seriously, it's YOUR house and you are within your rights to either tell him straight out that you don't feel comfortable discussing politics (or religion or anything that's sensitive in nature) and switch the subject. If he keeps it up he's being disrespectful and rude but well, that's often done among relatives.
IMO if he's ignoring your request of "No politics" then you'll have to ignore him. Don't answer him, don't rise to the bait. I'd just get up and walk out of the room or change the subject.
"I hate Obama"
"So how about those Yankees?" (or Red Sox or whatever..)
After awhile, when he realizes that no one is going to address his initial statement or he isn't getting a rise out of anyone he'll stop. (hopefully). He might be doing this to stir things up and cause some excitement so don't give him any.
I've been in this situation myself. I have friends who have certain, diametrically opposed viewpoints to current issues. They'll say something about health care or taxes or whatever and to be honest, I'd just as soon not get into it. So I'll just smile and say something like "Weather is nice lately" or "I'm going to see a concert next Saturday, what do you think of this band?" Or say something really inane and stupid. Eventually they get it.