I think this election, more than many others in the recent past, has touched on a lot of fundamentally-held beliefs in people. Both sides think their beliefs on any one of several social issues are blindingly obvious and the other side couldn't possibly be using any logic whatsoever. Several of the issues currently being bandied about have "scientific proof" provided by both sides, in the form of flat-out contradictory studies. Of course, both sides think the other one is supporting junk research just to make their political point stronger.
So while saying "I don't talk politics" is fine, it may not help because your bosses may truly, fundamentally not understand why you don't share their viewpoint. After all, any rational person would see things the same way they do, right? And what's more, science backs them up! You must be willfully blind if you don't agree with them! If only they could talk to you for a few minutes, they could find the hole in your logic! Since they like and respect you, they know you're not just crazy - but they don't understand how you could disagree. It's a confusing position to be in. (And I'll admit, I feel this way about a few of the issues on the table too - I've got friends I love and respect who disagree with me on the fundamentals, and I truly don't understand why. I respect their right to disagree with me, though.)
That said, "I don't talk politics" probably won't stop the questions. You will likely have to elaborate a bit on why: "Bosses, I really don't feel comfortable talking about politics with you. I know we don't agree, but we do respect each other. I don't expect I'll change your minds, and I trust you to not insist on trying to change mine. If you're really curious what [people on my political side] think about certain issues, there are plenty of places online to find good blog posts and newspaper articles which are much more eloquent than I could ever be. Debating politics here, though, feels kinda awkward and keeps me from getting other work done. So no hard feelings or anything, but could we just pretend it's the second week of November already and be done talking about it?"