Is it only your political views that your partner no longer is willing to respect?
If so, you need either just to stop discussing politics (which I would not be able to do, I may say) or tell him that you have a right to your opinions, as he has the right to his, but that you find his comments difficult to live with. Ask for a politer tone when politics are being discussed and no snide remarks about your views or the newspaper you choose to read.
Take a long hard look at the situation, because if heis suddenly incapable of respecting your political views, you need to ask yourself and him how your relationship is going to continue, and whether he respects your other views (and you his).
If the lack of respect is prevalent in other aspects of your relationship, I feel that now it the time for the pair of you to think very seriously about whether this is a bump in the road that you both can get over, or whether you are going down a dead end.
Sorry to be so pessimistic, but if you are going to break up over this, then it is probably better to do so sooner then later.