I enjoy discussing politics, at work too, however, you have to do it in a respectful way. Politics is like religion, you will never directly convince anyone of anything, but if you can expose them to new ideas, and watch them either incorporate or challenge these ideas, it's a really rewarding discussion. You also have to limit these discussions to willing participants.

In my time at Google, there were tons of people who felt they had the right answer, and had to convince everyone else who was wrong to come around to their views.