Actually, the letter was not a cipher. Plan D was the fourth of several studies organized by an opaque advocacy group, known as the Hub, to prepare for the depredations of the Trump era. The Hub is known in Washington for its sophisticated dark-money interventions in electoral politics. During the 2020 campaign, it also gathered up strategists, lawyers and activists to draft plans for a different kind of conflict.

The document is an artifact from a dangerous time: Warning that Trump would surely not concede defeat to Joe Biden, it advised Trump’s opponents to “assume the worst” would follow. It urged them to gird for a struggle not only with the president but with “institutions controlled or influenced by the GOP, including the courts.” The document forecast “militia and white supremacist activities through the inauguration — and, very likely, accelerated activity in the early months of a Biden administration.”

Plan D is sobering reading even today. It is a catalog of the defects in America’s electoral process and political culture that made it vulnerable to a rampaging demagogue— defects that some Democrats wanted to fix with drastic measures.

Should Biden lose narrowly, the report said, “layers of illegitimate structures and interventions will have contributed to it.” It closed with a warning against complacency even if Trump were to be defeated.

“A Biden win will not prove that our democracy is healthy,” the document argued, continuing: “Win, lose, or draw, we should perceive ourselves not in a singular moment of crisis but rather in what may be an era of existential challenge for American democracy.”

I first read the report soon after it was composed, when a source shared it as an off-the-record analysis to inform my thinking about 2020. At the time, I thought it was a creative assessment of potential worst-case scenarios, some of which struck me as rather remote. The January 6 insurrection was still months away.

In any event, I found Plan D more compelling than contemporaneous Democratic planning exercises that seemed more like high-concept role play for political elites. My colleague Sam Stein, then at The Daily Beast, reported on one “simulation” that foresaw the Biden campaign urging the entire West Coast to secede in a unit known as “Cascadia.” Simulation indeed.

Plan D was no game. It was devised as a battle plan. Reviewing the report years later, it is impossible not to be struck by the sense of urgency in the text — and the speed with which the impatient demand for fundamental change to American politics has dissipated among most Democrats.

So, I returned to my source and obtained permission to write about it now at a safe distance from 2020.

Back then, the group behind Plan D saw deep reform to the political system as a survival imperative for Democrats. If the party controlled government after 2020, the report said, Democrats must treat it as a “fleeting-once-in-a-generation (or perhaps lifetime) opportunity” to revise the political system. Among the targets of that proposed overhaul: a Senate biased toward rural red states, a Supreme Court stacked with right-wing appointees and an Electoral College that overruled the popular vote twice in two decades.

“First and foremost, we must rewrite the rules of our democracy. That’s doing much more than just the voting, corruption, and money-in-politics reforms in HR1 or the VRA renewal,” the document stated, referring to the centerpiece legislative offerings of the Democrats’ pro-democracy agenda. “We must commit to structural reforms that, at a minimum, include DC and Puerto Rico statehood and expanding the federal courts.”

Liberals must also “embrace more aspirational goals of ending the Electoral College and establishing a constitutional right to vote,” it continued, plus more basic aims like the elimination of the Senate filibuster. Should Democrats fail to achieve those aims, the report proposed divisive and punitive measures, like denying certain federal assistance to sections of the country that consistently reject Democrats and yet hold a veto over legislation because the system is tilted in their favor. Perhaps, it suggested, brute fiscal coercion would extract concessions from Trump country.

Today, these calls for invasive constitutional surgery seem nearly fantastical. Democrats captured the White House and Congress, but with legislative majorities so small that they could not even restore the Voting Rights Act, let alone add new Supreme Court justices, new states and new stars to the American flag.

Democrats still have a thick sheaf of legislative proposals for reforming campaign finance, congressional redistricting, voter registration, early and mail-in voting, federal election oversight and more. In December, Congress passed a bipartisan measure to reform the Electoral Count Act, the rickety 19th Century law that Trump’s allies sought to exploit in 2020 to obstruct the transfer of power.

But these days Democrats are not really promoting ideas to address the most distorted features of the American system. Far from crusading for DC statehood, they are squabbling among themselves over whether to nullify changes to the city’s criminal code enacted by left-wing local lawmakers. A short-lived flirtation with court-packing withered in a blue-ribbon presidential commission that issued an equivocal report.

For now, America’s liberal party is more comfortable thundering against changes to the number of ballot-collection boxes in the Atlanta area than openly discussing the profound unfairness of a system that awards equal representation in the Senate to South Dakota and California. Indeed, there are times when talking to Democratic leaders about threats to democracy can feel a little like consulting with a physician who speaks with eager authority about all manner of unpleasant illnesses — except the terminal disease you have actually contracted.

One Democrat who is eager to talk about that fatal ailment is Arkadi Gerney, the founding leader of the Hub who recently stepped down as its executive director. A longtime gun-control advocate who previously worked for the Center for American Progress and Michael Bloomberg’s City Hall, he was one of the lead authors of the Plan D report.

In a reflective conversation this winter he told me Democrats should be far more attentive to the rightward bias of the country’s political institutions. Much of American history, he argued, is the story of one popular movement or another driving at changes to democratic political system far grander than the admission of several new states.

“In this country, we had a history of fixing flawed elements of our democracy, generation by generation, from slavery in the post-Civil War amendments to the Constitution, to women’s suffrage, to changing the age to vote to 18,” Gerney said. “And that process, in the last 50 years, has gotten stuck.”

Part of the problem, he said, is that America’s most unfair political institutions are self-perpetuating. You cannot do much to change the Senate and the Supreme Court without the assent of the Senate and the Supreme Court.

Still, Gerney insisted, awfully difficult is not the same thing as impossible. He pointed to voters’ volcanic indignation about the Dobbs decision as the kind of popular mobilization that could ultimately yield foundational change. We’ll see.

The good news in Plan D is contained in passages where its authors missed the mark: their warning, for instance, that the conservative judiciary might aid Trump’s election sabotage (it did not) or the suggestion that Democrats might need to give Trump amnesty from prosecution to ease the transfer of power (multiple ongoing investigations of Trump show otherwise).

Most encouraging may be what the report misjudged about how the business of legislating would unfold under Biden. Unless the filibuster were abolished, the document warned, Biden’s agenda could meet a miserable death in “Mitch McConnell’s legislative graveyard.” Plan D judged it largely futile to seek bipartisan compromise, since whatever Democrats do, “Republicans will accuse us of murder, socialism and worse.”

That last part is true of many Republicans. On the whole, the GOP remains an angry, Trumpy party. Yet some — including McConnell — joined with Democrats to pass a hefty infrastructure law, an aggressive industrial policy for the high-tech sector and more. Even with the structure of the Senate and the courts still firmly in place, Democrats still managed to enact a landmark climate law that has unleashed a global clean-energy arms race.

Whether that was a sufficient use of a once-in-a-generation opportunity is a question Democrats must answer for themselves. The 2024 election will show if it was enough to avert the return of Trump himself.