Is there a huge core of committed ideological conservatives who have not voted before because they had only “moderates” on the ballot? Other than the fact that no objective person could look at the policy positions of John McCain and Mitt Romney as moderate, there is no evidence; the only real parallel to draw on for the theory is Barry Goldwater in 1964. Important as voter identification and get-out-the-vote efforts are, they do not convince chronic non-voters to vote. And, of course, a truly purist ideological campaign would stir a clear counter-reaction on the other side, diluting its impact.
The more important question, in many ways, that flows from this theory is about governing. It is here that the Bernie Sanders approach needs more dissection. Let’s say Sanders is accurate enough that his nomination would lead to his election via a bump in turnout from young voters and other populists disgusted by inequality, the billionaire class privilege and the distorted campaign-money system. Let’s say that he survives the billion dollars that might be spent by the Koch brothers’ alliance, the business community, the Republican candidate, and the Republican Party to destroy him as an unreconstructed socialist who will raise everybody’s taxes.