I definitely understand where you're coming from. I would be troubled if I discovered my T voted a certain way in the last US presidential election. (He hasn't told me straight out, but has said enough that I'm sure of who he didn't vote for.)

Still, even if your T would not tell you her political opinions, maybe this is a good opportunity to talk about how you deal with people who think differently than you in general. Can you disagree with someone politically and still see them as a good person or a friend?