Is this just another 'October Surprise'?
A game changing event usually occurring in the month of October before election, which can boost, or damage one candidate's chances and critically change the course of an election.
US has a history of October surprises in an election year. Leaving out the obvious October surprises from this year, here's a small list from 2016 and previous years.
https://www.bbc.com/news/magazine-19887898