As my thinking's evolved over the last year, I've given a high priority to not losing sight of the fact that not all on the Right are dogmatic extremists, and that some on the Right, those clustered in the region of political space I call "Classic Conservatives", can be counted upon to do the right thing when the chips are down.

I've been trying to come up with a depiction of political space, along the lines of those two-dimensional plane surface charts we've seen a lot of. Trouble is, I think mine's going to end up a topological nightmare, with multiple dimensions, some of which are of fixed length but open, and others are closed--circular. But to restrict myself to the traditional one dimension, I see a fractal trifurcation that reminds me of the Founder's handiwork and their love of threes:

{ Left, Center, Right }

Which trifurcates naturally into:

{ { extremist, partisan, moderate }, { left-leaning, centered, right-leaning }, { moderate, partisan, extremist } }

I think that it's the partisans who are most inclined to make the sort of calculation of political advantage that you describe. Extremists can be counted upon to stay the course. And whether the centrists are "following their consciences" or "blowing in the prevailing wind" seems to depend entirely on whether they're moving away from you or toward you ("you" the notional partisan). But, in any case, I think the Center's calculations are more complicated and jockeying for position is a minor theme. I think it's simply the case that support, as expressed by votes, has evolved over the last year:

{ { extremist, partisan, moderate { left-leaning, },centered, right-leaning }, { moderate, partisan, extremist } }

to

{ { extremist, partisan, moderate { left-leaning, },centered, right-leaning }, { moderate, partisan/partisan, extremist } }

Right partisans are in play at the moment, for the reasons you give. Moderate conservatives have recently made up their minds, right-leaning Centrists a while earlier. The line's moved steadily from left to right over the course of the last year.

I tend to think of "rank and file Republicans" as disproportionately moderate, in the sense that the GOP machine has given voice in recent years only to the partisan and extremist factions, while ignoring and sometimes even disparaging their moderates; but the moderates haven't gone away, by any means. I think that now is their time, and what we're going to see in the GOP--regardless of the outcome of the election--is an internal revolution in the GOP as the moderates and Classics take back their party. That can only be a good thing, and that's why, despite Tom's dark predictions about the heads of Democrats exploding if the election doesn't go as predicted, I'm actually already satisfied that things will take a turn for the better no matter what. The GOP is going to have at least a near-death experience, and the shock will be good for its system, and good for America. I'm a happy camper. The Universe is unfolding as it should.