I have a few friends who could be described as liberal, but I tend to more political on the internet than I am in real life. I rarely discuss politics or religion with friends, regardless of their stance. That said, I’m not very close to any one who is rabidly liberal. My left-leaning friends are mainly so because of their upbringing; the son of a Democratic state rep, a daughter of a union president, my black friends, ect.
A few years ago, I did stop talking to a friend who became a Truther weirdo, but there were also other issues.