On his present trajectory, President Trump is heading for a whopping defeat in November. The Economist says there’s nearly a 99 percent chance that Joe Biden will win more popular votes and around a 90 percent chance that he will win more electoral college votes. But what if Trump won’t concede defeat? That is a nightmare scenario for our democracy that could make the 2000 showdown over Florida’s hanging chads seem like a grade-school dispute by comparison.

Trump is already laying the foundation to dispute the election outcome with his incessant claims that “Mail-In Ballots will lead to MASSIVE electoral fraud and a RIGGED 2020 Election.” Election officials label such concerns as “preposterous” and “false.” But they will serve as an excuse for the Republican Party to purge voter-registration rolls, limit mail-in ballots, close polling stations in minority areas and challenge in-person voting by minorities. Whatever it takes to win.

It’s doubtful that anything Trump does will produce a popular-vote victory; he lost by nearly 3 million votes in 2016 and will probably lose by a greater margin this year. But it won’t matter if, by election night, he is within spitting distance of an electoral college victory.

I recently took part in a “war game” to see what would happen under those circumstances. The session was organized by the Transition Integrity Project, a nonpartisan group founded by Rosa Brooks of Georgetown Law School and Nils Gilman of the Berggruen Institute. The scenario we were given predicted a narrow Biden victory in the electoral college: 278 to 260. Various participants played the role of the Trump campaign, the Biden campaign, Republican and Democratic elected officials, the news media, and other key players to see what would happen next.