The New Republic's Noam Scheiber has got hold of the Romney campaign's ineffably wrongheaded "final internal polling numbers," which of course led the team into an equally ineffable dreamland of ultimate victory. Scheiber claims to have learned why the Romney camp was "so sanguine about its own polling, even though it often parted company with the publicly available data," but I don't quite see the answer.
GroupThink is an obvious one--cheering crowds lending a deceptive ring of broadbased support; internally organized smugness, in which the thundering righteousness of one's own candidate is self-evident; all those campaign staff meetings in which that heck of a job each staffer is doing is duly noted, but little else--yet GroupThink, as an answer, fails to satisfy. This particular phenomenon is generally isolated from reality, whereas the Romney camp's internal polling numbers were swimming against an unignorable stream of poundingly contrary evidence.
The real answer may be much simpler than anything found in organizational theory: Mitt Romney, the indisputably worst nominee in American presidential history, was backed by a team of indisputably total incompetents.