I think the Democratic field is too hard to call at this point. Since they will have been out of power for eight years the field is going to be wide open to a huge number of politicians.
Mark Warner is an extremely obvious choice, and since I voted for the man as governor there’s a good chance I’d vote for him as President (and I’m a Republican), so I’d say he’d be an extremely electable candidate for the Democrats.
Warner has a 75% approval rating here in Virginia, a State that is traditionally Republican. When you start doing electoral math this guy has an amazing chance of picking up Virginia for the Dems and winning Florida handily.
The problem with politicians like Warner (and McCain, for that matter) is when you’re right in the center, or perceived to be in the center, you have some of the party faithful doubting you. And in primaries the more extreme wings of both parties have a lot more power than they do in the general election.
If Warner can get through the primary minefield, I think he’ll be President in 2008.
From the Republicans we have a lot of people who are standing out now, and have been standing out for awhile. McCain, Jeb, Frist (diminished by allegations of insider trading), even Giuliani (would never get out of the primaries.)
Of all the possibles out there I’d want Warner or McCain to be president. I don’t even know if either of them will get elected. McCain was defeated because he wasn’t an “insider” in the GOP in 2000, and while he has tried to cozy up to the Republican leadership I don’t know that he’s done enough to grab the nomination, plus his age is going to be a strike against him.