A Startling Document Predicted Jan. 6. Democrats Are Missing Its Other Warnings.

Weeks before the 2020 election, a secret 87-page document outlined in matter-of-fact language the threat posed by Donald Trump’s still-to-come campaign of election denial. The private paper — the existence of which has not been reported before — forecast with chilling confidence the likelihood of violence during the presidential handover and proposed a far-reaching set of political reforms to thwart Trumpism in the future.

Americans remember that dark winter well. But the impetus for structural change has faded, even among Democrats who still privately seethe about the country’s broken political...