Here's a followup question. Has a candidate ever recovered from this kind of deficit this late in the election season and won?
Breckenridge was way ahead of Lincoln in October of 1860, till the October Suprise emerged and we learned that Breckenridge was taking pictures of women for Playboy magazine.
Just kidding. Polling wasn't bigly scientific at the time, but people were so moved that the turnout was huge. Something like 81%. I don't know if that has ever been bested.
You ask a good question, and I don't know the answer, but it's a really, really weird election this year. How many candidates in the first debate said, in answer to the very first question, that if he is not the party's nominee that he will not necessarily support the party's nominee, and yet manage to win that party's nomination, even as every major elected official from that party publicly denounced him? I don't think that the past is necessarily a good gauge this year.