Donald Trump holds a dominant position in national polls in the Republican race in no small part because he is extremely strong among people on the periphery of the G.O.P. coalition.
Read as "Not establishment GOP"
Maybe these voters are going Howard Beale and show up in November?
Trump is showing a rather surprising broad based appeal across most demographic groups which isn't being touted much at all by MSM, rather the slant is on telling those groups how bad a guy he is to them.
He is strongest among Republicans who are less affluent, less educated and less likely to turn out to vote. His very best voters are self-identified Republicans who nonetheless are registered as Democrats. It’s a coalition that’s concentrated in the South, Appalachia and the industrial North, according to data provided to The Upshot by Civis Analytics, a Democratic data firm.

http://www.nytimes.com/2015/12/31/upshot/donald-trumps-strongest-supporters-a-certain-kind-of-democrat.html?_r=0