Donald Trump dominates the national polls, but he's second in Iowa, according to the RealClearPolitics average. And, as I pointed out in a recent column, "The more that polls refine for the likelihood of a respondent actually voting, the worse Trump does."
At first glance, this suggests that Trump supporters are far less likely to actually vote than other voters are. But "likely voter" methodology used by pollsters is some combination of psychology and modeling off of past elections. Trump, it's safe to say, is different from candidates in past elections. One reason people don't vote is that they think all candidates are similarly awful — exactly the sort of dissatisfaction into which Trump taps.
Could Trump turn unlikely voters into voters?
"The thing about appealing to people who don't usually vote," Political scientist Thomas Holbrook told The Daily Caller's Jamie Weinstein, "is that they don't usually vote."