It isn't quite here yet, but at some point fairly soon Republicans will en masse make it clear that their opinion of Bush is only half a notch above their opinion of Nixon. The missing history - and context - in this is that in 2000 John McCain was the neoconservative poster boy. The Weekly Standard Gang was his posse. The owner of the Free Republic at one point purged all of the Bush supporters as he too was a McCainiac. The Bushies then fled to lucianne.com.
Their foreign policy is Bush's post 9/11 foreign policy. McCain may be more competent than Bush - I have no idea - but a McCain presidency probably would've brought us to Iraq sooner, not later.
Once upon a time we all imagined that McCain's presidential aspirations were doomed by age, or illness, or by his unpopularity with the True Believers. I still think it's the case that a decently funded skillfull primary campaign will easily destroy him, but only if such a campaign exists. The Powers That Be may decide he's their only hope and if so they'll line up.
Right now Democrats are lining up to have their pictures taken with McCain instead of understanding that he'd be an even more dangerous president than Bush. They need to start understanding what is at stake.