If he does lose, is he going to blame himself? Of course not. A lot of people will get the blame -- but this portion of Breitbart's current front page may reveal the main argument he'll make to excuse his loss:
Mainstream pundits will be saying that it all began to go to pieces for Trump when he spent nearly a week attacking Khizr and Ghazala Khan for the speech Khizr Khan made at the Democratic convention. Trump will agree -- but he'll say he was dealt low blows, first by a man regarded in the Trumpite circles as a radical Islamist who'd like to replace the Constitution with sharia law, then by the Republican Party, which, as one of the headlines above argues, was "stupid to create a no-fire zone around" Khan. Stab in the back!
Meanwhile, in the near term, I wonder how Trump is going to explain his terrible numbers in the Fox poll. I wonder if he's going to see a conspiracy in the fact that his pal Roger Ailes was forced out at Fox, after which he sank in a Fox poll. Evil politically correct liberals are everywhere! They've completed their infilitration of Fox! Yeah, that might be his explanation.