From what I read, the problem Obama has--tactically--in Iowa, is that many of his supporters are quite young voters. And the Iowa caucus will take place over the Christmas break-- when the vast majority of college students will not be in Iowa. They therefore will not be able to vote there--if that were possible--and will not even be able to help ferry voters to the polls or do other work for Obama.

Whereas Hillary's strongest supporters are appear to be older women--who will be there--and tend to vote in large numbers.

However, if Hillary does not win in Iowa by a large margin, Edwards and Obama can team up afterwards--and stop her.

The visceral anti-Hillary sentiment in the country is huge. Not so high for Edwards and Obama.