You do realize that McCain didn't pick Lieberman, right?
Yes. I do recall that. Don't you think it's troubling that McCain didn't just think about Lieberman, but he actively entertained the idea and actually explored the possibility with GOP leadership?
It's not at all dissimilar from asking your wife it would be OK to have an affair. Somethings are just too stupid to be asked - asking if it would be OK to put a Democrat on a GOP ticket is one of those things.