My colleague John Judis (via e-mail) and commenter ilnoca both make a great point: Given the closeness of the race in Iowa, the difference may well be who supporters of Biden, Richardson, and Dodd migrate to if/when their caucus-groups are declared non-viable. (For those confused by terms like "non-viable," Mike will be posting a piece on caucus mechanics in the next day or two.) John suspects that these people are headed Clinton's way, given that they're probably attracted to experience and Clinton, fair or not, has been labeled the most experienced of the front-runners. But I'll be asking people explicitly about this when I'm at events this weekend and reporting back on what I hear.

--Noam Scheiber