Look at these polls (cribbed via Daily Kos). Look CLOSELY, beyond, just the "Newt winning big" part. DO you see what I see?
In a few of these Bachmann alone is ahead of Perry, but in all of them, (Bachmann + Santorum) > Perry.
IOWA (ABC/WaPo): Gingrich 33, Paul 18, Romney 18, Perry 11, Bachmann 8, Santorum 7, Huntsman 2
IOWA (CBS/NYT): Gingrich 31, Romney 17, Paul 16, Perry 11, Bachmann 9, Santorum 4, Huntsman 1
IOWA (CNN/Time): Gingrich 33, Romney 20, Paul 17, Perry 9, Bachmann 7, Santorum 5, Huntsman 1
IOWA (Des Moines Register/Selzer): Gingrich 25, Paul 18, Romney 16, Bachmann 8, Cain 8, Perry 6, Santorum 6, Huntsman 2
IOWA (NBC/Marist): Gingrich 26, Romney 18, Paul 17, Cain 9, Perry 9, Bachmann 5, Santorum 5, Huntsman 2
IOWA (PPP):: Gingrich 27, Paul 18, Romney 16, Bachmann 13, Perry 9, Santorum 6, Huntsman 4, Johnson 1
IOWA (We Ask America--R): Gingrich 30, Romney 16, Paul 14, Bachmann 13, Perry 7, Santorum 4, Huntsman 3
What's paralyzed the movement conservatives in Iowa is the inability to choose between Santorum and
Bachmann. If one would bail on the race and endorse the other, the supporters might not automatically follow suit, but the natural inclination would be toward that second choice.
It happened naturally in 2007: Mike Huckabee knocked Sam Brownback out of the race post-Ames, and emerged as the united choice of social conservatives. But Michele Bachman actually got a negative bump out of her Ames win, as Rick Perry's entry into the race completely stepped on the story.
But let's hypothetically say it happens. Santorum or Bachmann drops out and endorses the other, and the supporters follow. That would bump her or him up past Perry and very close to the second tier of Paul and Romney. At that point, the survivor, Bachmann or Santorum, is a live round, and starts peeling support off of Perry and even Newt.
I'd say the odds of that scenario are slim, but it's an opportunity the social conservatives are missing.