From NBC’s October 19 post-presidential debate coverage:
NICOLLE WALLACE: He by refusing to say that he would accept the results of the election on November 8th, he may as well have laid down in his own coffin with a hammer and nail and pounded it in himself. No voter wants to hear that a participant who has been very -- he won the primary. How could the primary have not been rigged against him if he won so overwhelmingly? To say that he will not accept the results of a hard-fought and robust election where he's been pretty close in the polls until very recently is really just a disqualifying statement in the views of many voters. And really, the tragedy for his base of support which is very agitated and very sort of anxious to see him do better, is they got that improved performance from him on questions like trade. They will like what they heard from him on the economy. And they will like some of his other answers. But by saying he won't accept the results of the election, that was just a lights out moment in American politics.