I posted earlier at Plum Line about the 20 percent of Iowa caucus-goers who have been with Michele Bachmann and Newt Gingrich in recent polls but could wind up elsewhere if — if — those two candidates collapse. Which I think is very possible, but hardly certain.

But suppose it happens. And suppose that this week’s flavor, Rick Santorum, benefits, jumping solidly into the top three and perhaps even winning.

So here are some questions…

1. Could Rick Perry keep going? Under this scenario, Perry doesn’t melt down, but also picks up little or nothing from voters who had been undecided or with Bachmann or Newt. That gives him a solid 4th place. Is it enough for him to get past a dismal showing in New Hampshire and on to South Carolina? I suspect not, but it sort of depends on….

2. What do Republican party actors think of Rick Santorum, anyway? My impression is that so far they’ve basically ignored him, believing (as I did) that he was just an implausible nominee. That was true. But if he can finish third (or better!) in Iowa, and better than everyone but Paul and Romney, do those who don’t want Romney start breaking sharply for Santorum? The general reaction I’m hearing to the Santorum semi-surge so far has been to dismiss him, but I’m increasingly unsure that’s correct. As I said earlier this week, if the only real black mark against Santorum was that he got clobbered for re-election, it seems to me that his surge (if it happens) will be a lot less hollow than most of the others this year. Although he’ll still, of course, have to perform well to keep it going.

3. Will Bachmann and Newt drop out? Again, this is on the assumption that they collapse down to 5 percent each, give or take a few points. Normally, both would, but neither is necessarily playing by the normal rules, or constrained by the normal forces that push losers to stop going.

[Cross-posted at A plain blog about politics]

Jonathan Bernstein

Jonathan Bernstein is a political scientist who writes about American politics, especially the presidency, Congress, parties, and elections.