argumentative brother

My brother is a lawyer who is extremely involved in politics. He has very strong opinions, goes to political meetings and has friends in political circles. He constantly talks to me about political beliefs. I tell him that I vote but I won't say for whom. I won't engage in debates with him. I never go to the meetings he invites me to. He tells me that I am what is wrong with the country because I don't have a passion for social policy. I tell him that is the same as an English professor chiding him for being against education because he does not read Shakespeare. We just have separate interests, but he can't just leave me alone because he is so zealous about his politics. We are at the point of not inviting him to our home any more. It's that bad. No amount of discussion will cause him to back off his lectures.
I'd be interested in knowing how to salvage a relationship that is on the verge of falling apart.