Nov. 4 will be a day, said one of the former senior intelligence officials, “when he’ll want to match word with deed.” Key officials in several parts of the government told me how they thought the progression from the 3rd to the 4th might go down.

They are loath to give up too many precise details, but it’s not hard to speculate from what we already know. Disruption would most likely begin on Election Day morning somewhere on the East Coast, where polls open first. Miami and Philadelphia (already convulsed this week after another police shooting), in big swing states, would be likely locations. It could be anything, maybe violent, maybe not, started by anyone, or something planned and executed by any number of organizations, almost all of them on the right fringe, many adoring of Mr. Trump. The options are vast and test the imagination. Activists could stage protests at a few of the more crowded polling places and draw those in long lines into conflict.

A group could just directly attack a polling place, injuring poll workers of both parties, and creating a powerful visual — an American polling place in flames, like the ballot box in Massachusetts that was burned earlier this week — that would immediately circle the globe. Some enthusiasts may simply enter the area around a polling location to root out voter fraud — as the president has directed his supporters to do — taking advantage of a 2018 court ruling that allows the Republican National Committee to pursue “ballot security” operations without court approval.

Would that mean that Mr. Trump caused any such planned activities or improvisations? No, not directly. He’s in an ongoing conversation — one to many, in a twisted e pluribus unum — with a vast population, which is in turn in conversations — many to many — among themselves. People are receiving messages, interpreting them and deciding to act, or not.