Over and over we hear and read that this is the most important election of our lifetime. I could argue (and did at the time) that 2000 was more important, but put that aside for the moment, that's just squabbling.
I can certainly see why anyone on the left would frame this election that way. I can even see why actual conservative republicans might frame it that way after they've had four years to think about it.
But if Bushies frame it this way (anyone know of references?), that's pretty telling. I realize they don't live in the real world, but do they really think that Kerry is way, way outside the mainstream of past Democratic nominees? I doubt it. Instead, by framing it this way, they acknowledge what we realize. This isn't about a quantitative swing of the pendulum left or right. This is about a qualitatively huge gap between two versions of the American future. And if Kerry isn't too outside the mainstream, then Bush must be.
Even if they claim that terrorism changes everything, Kerry is still not really outside the mainstream of past dealings with terrorism. So they must be saying that terrorism changes everything, hence we need radical change in America, and Bush is the one to bring it = Bush is the radical.
Incidentally, this is a small media framing victory for the left. Because if people think of it as the most important, then the natural question is, what are the differences which are so much bigger than the differences in the past?