Perhaps but he is pro choice, pro gay rights, pro gay marriage, pro affirmative action, pro gun control and several other pros that are identified as clearly liberal agenda items. I am reasonably certain he would describe himself as a liberal.
Is he a president-bashing, conservative-hating, flaming liberal? No way, so you are right that in that sense he is quite moderate. He is also well reasoned and can quite intelligently articulate why he supports the view that he holds.
He can also support a 'conservative' cause when it makes sense to him and he can criticize his side when they get it wrong. I find this refreshing and honest and pretty cool.