I saw the chart below today, was wondering where to put it -- will fit right in here.
In these now Divided States of America, the "two [political] sides" have become so embedded, so "inured", that huge blocs of voters are now "magnetized". That is to say, the "name" of the candidate doesn't matter, nor do the politics, platform or even the perceived competence of said candidate.
The magnet voters (on both sides) will by default swing towards their corresponding poles. They cannot become "de-magnetized", even by "a performance" as bad as was ol' white joe's the other evening.
Look at this chart:

In nearly every matchup, "the difference" between Mr. Trump and the dem/communist candidate is... 3%.
Two matchups... 2%.
Of course there is "the mushy independent middle", and this time around, the "breakaways" who will vote for Bobby jr. and Cornell West.
But it's well-nigh impossible to gauge the sentiments of "the independents", who by nature are unable to commit themselves to any candidate almost right up to the last moment. They will "wave like the wheat" and bend to and fro with the prevailing political winds...