I had a thought. All this mystery movement to Carson? I wonder if the Trump supporters in part refuse to take part in polls. Particularly those from the network. Also, three of four polls showing Carson ahead in Iowa were from colleges, and covered the same period of time. Trump folks are more likely to be not prone to be interested in some whiny college kid on the phone, where as Carson’s folks might be more patient. The supporters are a reflection of the personality of their chosen candidate.
I don’t think it’s a mystery at all. I believe that Walker’s voters went to Carson after Walker dropped out so that was worth maybe as much as 5 points. I also think that Trump lost some support when he attacked GWB over 9/11 and I don’t think evangelicals are into Trump. Evangelicals are more drawn to Carson, despite the fact that Trump claims “evangelicals love him”.
I don’t think poll methodology has anything to do with it, otherwise why would polls in the previous months favor Trump and recently the same polls with the same methodology favor Carson?