Biden/Harrris---if you talk 'em up, you take 'em up; if you talk 'em down, you take 'em down.
One type of "undecided" voter is not thoughtfully considering the merits of the candidates; they are trying to decide who will likely win on November 3rd. They want to vote for the winner. Period.
Many have no idea what the candidates are promising to do. It does not matter. With their vote, they want to join the "winning team".
This is how perception can, indeed, become reality. No one voice decides how these folks vote. But, the cumulative effect of how people respect or disrespect a candidate, how enthusiastic and confident his or her supporters seem to be and, as a result of this cumulative effect, how the media SEEMS TO FEEL about the candidate. Tone of voice, facial expressions, animation---the "undecideds" soak all this in as they watch TV and try to "go with the flow". And, some of those media commentators are also watching you---and me---and "the man on the street" to see which way "the flow" seems to be going because they want to "win" also.
Is this a sad way to cast a vote? Of course, but guess what: their sad shallow vote counts just as much as your carefully informed vote.
If the only person they could watch and listen to was you, would they decide you were supporting a winner?