Just a quick reality check. There have been six Iowa polls released this week, five of them based only on surveys begun after Christmas. Rick Santorum is certainly surging, in the sense that he was probably in sixth place before and appears to be in third place now. But careful...at least from what we've seen yet, his surge is still more semi- than certain, at least if we're talking about a strong finish.
In particular, here are Santorum's leads over Rick Perry in those five polls (four via Silver, plus NBC here): 0, 2, 2, 3, 1.
Impressed? I doubt it.
Now, if we go beyond the horse race numbers, it's clear that there's good news for Santorum in that his favorable ratings beat Perry's, at least in the ones I've looked at. And buzz and hype are clearly on Santorum's side. On the other hand, Perry is presumably going to be massively outspending Santorum on ads over the last few days. There's also the question of organization...I'm really not certain who has the advantage there, or how that will figure in.
I'm just saying: from the numbers so far, it ain't there.
UPDATE while I'm writing....and now a new poll is out with a 7 point gap between them. With Bachmann surging up to 12%! Maybe that's right...I don't know; it seems unlikely to me that Bachmann's week has helped her, but perhaps it has.
I guess I'll tie it all together by just emphasizing (1) Iowa is really hard to poll, and (2) try not to make too much of a lot of relatively small differences in polling numbers.