From what I've heard from his old buddies, Elvis was basically apolitical. He didn't vote and didn't want to endorse any particular person or party -- he really meant what he said at the 1972 NYC press conference:
Mister Presley, what is your opinion of war protesters? And would you today refuse to be drafted?Honey, I'd just, I'd just soon keep my own personal views about that to myself. 'Cause I'm, I'm, I'm just an entertainer and I...I'd rather not say.
Do you think that other entertainers should also keep their views to themselves? No.
What about politics? I'm not involved in that at all. I'm just an entertainer.
It sounds like he was largely a social liberal (especially in regard to issues of poverty, religious tolerance, and race) but that he still adhered to some 'traditional' conservative values, perhaps mainly when it came to women and law enforcement...though even that's not cut and dried. I do know that he'd have considered himself a patriot. Unfortunately, there's long been an element in US politics and government that trades on patriotism to commit all sorts of bad stuff.
I think he'd have loved Clinton and I have no idea how he'd react to Bush...you've also got to factor in personal growth that might have set in after the age of 42 (he might even have grown up, at last) but I think that, if he did go the my-country-right-or-wrong route, he'd be reconsidering by now. I highly, highly doubt that he'd be a true Freeper.