Well, really I have only one, that Huckabee will do a lot better than the polling trend of 12% or so.
If you look at things like this report of large crowds for him, and the statements of the Republican establishment and the Washington punditocracy* to the effect that Huckabee supporters are mouth breathing morons, which would tend to have people not telling pollsters that they lean his way.
Additionally, independent voters are more likely to vote in the Democratic primary, simply because they believe that the next president will be a Democrat, which leaves a higher proportion of hard core conservatives voting.
I’m calling for 17+% for Huckabee. (A clarification, I’m not calling a win, just that he breaks 17%)
*Which might be better described as a Kakistocracy.