I think the trends are opposite, actually. As the GOP gets younger (thanks to the Establishment getting old and retiring/dying/being primaried out), the move is more towards libertarianism (see, inter alia. Rand Paul). Meanwhile, as the Democratic Party gets younger, they are moving more towards statism (see. inter alia, Tumblr, twitter mobs, and the American collegiate left). The complaints aren't that Obama isn't liberal enough, it's that he's not being sufficiently authoritarian in his progressivism, which is the direction in which that party is moving (the same phase the Republican Party went through in the 70s, only they wanted to be more authoritarian towards traditionalism).