WASHINGTON — President Donald Trump’s and Democratic rival Joe Biden’s campaigns are assembling armies of powerful lawyers for the possibility that the race for the White House is decided not at the ballot box but in court.

They have been engaging in a lawyer’s version of tabletop war games, churning out draft pleadings, briefs and memos to cover scenarios that read like the stuff of a law school hypothetical more than a real-life case in a democracy.

Attorneys for the Republicans and the Democrats are already clashing in courts across the U.S. over mail-in ballot deadlines and other issues brought on by the coronavirus pandemic. And as Mr. Trump tries to sow doubt in the legitimacy of the Nov. 3 election, both sides have built massive legal operations readying for a bitterly disputed race that lands at the Supreme Court.

“We’ve been preparing for this for well over a year,” Republican National Committee Chief Counsel Justin Riemer said.

On the Democratic side, the Biden campaign’s election protection program includes a special national litigation team involving hundreds of lawyers led by Walter Dellinger, acting solicitor general in the Clinton administration, and Donald Verrilli, a solicitor general under President Barack Obama, among others.

Both sides are informed by the experience of the 2000 election, which was ultimately decided by the Supreme Court in Bush v. Gore. But this year — because Mr. Trump has pushed false claims about the potential for voter fraud with increased voting by mail, sowing doubt about the integrity of the result — lawyers are preparing for a return trip before the high court.

And, in an extraordinary twist, the president has pushed for his nominee to the Supreme Court, Judge Amy Coney Barrett, to be seated as soon as possible if she is confirmed as expected Monday, saying it’s important to have a ninth justice to decide any election disputes.

First Published: October 24, 2020, 4:56 a.m.