From Rolling Stone:

Over the past year, Team Biden has been conducting war games, crafting complex legal strategies, and devoting extensive resources to prepare for, as one former senior Biden administration official puts it, “all-hell-breaks-loose” scenarios. The preparations include planning for a contingency in which Biden’s margin of victory is so razor-thin that Trump and the GOP launch a tidal wave of legal challenges and political maneuvers to rerun his 2020 election strategy: declare victory anyways, and try to will it into existence.