I also live in an area where my political beliefs are more of a minority opinion and the majority of my friends identify with the majority opinion. I've certainly been in positions where friends have assumed I'm a member of the majority. Fortunately, my friends are well, my friends and they all have a good sense of humor. Because of that, when statements are made about people of the Glitter party, I usually respond with humor and say something like, "Hey, you know I'm a card-carrying member of the Glitter party! Can't you tell by my radiant sparkle?" I embrace it with humor and sometimes faux offense that they would recognize.
It may be because of our group dynamics, but I've always had success with that. They realize they've spoken too openly and perhaps offensively around a friend and are humbled/apologetic and then usually respond with some silly compliment like "You're just so cool I totally assumed you were a Dazzle".
I don't know how that would work for your group, but using a bit of humor can put people on notice that you have different beliefs without putting them on the defensive or shaming them. You bring it up in a light-hearted way and it gives them an opening to respond back in a light-hearted way. It also allows you to deflect further political conversations. "So you're a Glitter? Well, how do you feel about the economy blah-blah-blah?" And you can say, "You want to know how I feel? I feel like another glass of wine/slice of pie". If they push a bit you can continue to be light/upbeat but demonstrate you aren't going to get into a conversation about it and they take the hint.