If — and it’s a huge if — the polls are right, Joe Biden is about to post the largest popular-vote victory in the six presidential elections held in the 21st century. There are plenty of obvious explanations for his lead, mostly having to do with his opponent’s disastrous presidency. But there’s a more revealing, if esoteric account: Biden is also the first candidate to follow the electoral formula laid out in “The Emerging Democratic Majority,” a 2002 book that promised Democrats a route to enduring dominance of American politics.

Still, Democrats burned out on the Trump years shouldn’t get too excited: If Biden is the first “emerging Democratic majority” candidate, he’s also likely to be the last.

In the book, John B. Judis and Ruy Teixeira argued that Democrats were poised to take advantage of America’s transition to a postindustrial society by, among other things, advocating for investment in education, taking on income inequality, championing LGBTQ rights and allowing instances of GOP racism to backfire in an approach they dubbed “progressive centrism.”

Those positions, they suggested, could create a party that would “consistently take professionals by about 10 percent, working women by about 20 percent, keep 75 percent of the minority vote, and get close to an even split of white working-class voters.” Given shifting demographics, the book said, those margins would make for a new, dominant electoral majority.

This theory captured the imagination of progressives who detested George W. Bush’s neoconservatism and longed for a durable, liberal approach to government. Some even argued that Barack Obama and Hillary Clinton were bringing about this new Democratic future — but neither nailed the formula.

In 2008 and 2012, Obama overperformed Judis and Teixeira’s benchmarks with the “emerging” pieces of the coalition while keeping enough blue-collar White voters onboard to win. But Democrats lost some of their underlying strength with White working-class voters, and Democrats suffered disastrous defeats in the 2010 and 2014 midterms. Clinton lost the 2016 election when she departed more decisively from the game plan and traded blue-collar Whites for suburbanites, rather than finding a way to keep both constituencies in the tent.

But Biden’s coalition, at least as captured in an October Pew Research Center survey, looks a lot like the one envisioned by “The Emerging Democratic Majority.”

Biden’s lead over Trump is bigger than Clinton’s ever was, and, according to Pew, Biden is accomplishing that by capitalizing on “emerging” groups. He’s ahead by 20 points among college graduates, 16 points with women and 34 points with Latinos. He isn’t close to “half” of the White working class, but multiple data sources show him improving on Clinton’s numbers by roughly 10 points. Biden is running slightly behind Clinton with Black and Hispanic voters — but that may just put him more in line with Judis and Teixeira’s benchmarks, which Obama exceeded.

And, among the candidates who sought the 2020 Democratic nomination, Biden is the best proponent of Teixeira and Judis’s package of ideas. They wrote that the movement would be “a corrective to this Republican counterrevolution — an attempt to come to terms with what was positive and enduring in the movements of the sixties and in the transition to postindustrial capitalism. It does not represent a radical or aggressively left-wing response to conservatism, but a moderate accommodation with what were once radical movements.” That certainly sounds more like Biden than it does Bernie Sanders or Elizabeth Warren.

In the short term, this is all great news for Democrats: It means that Biden and the Democrats secure a large, balanced majority capable of enacting new progressive laws, and possibly able to mitigate losses in a low-turnout midterm.

But don’t expect Democrats to stretch this coalition into the fabled, permanent majority. Reaganism stopped working for Republicans when taxes were lower and the Cold War had given way to the much-less-successful war on terror; “progressive centrism” likewise has an expiration date. Eighteen years have passed since “The Emerging Democratic Majority” was published, and eventually America will finish its transition to a post-industrial society. When that happens, “progressive centrism” will no longer seem responsive to the most pressing problems of American society.

And once Biden and the progressive centrists are out of power, the prophecy of an emerging majority may become self-defeating. If Kamala D. Harris or another more progressive Biden successor overreads the stability of their coalition, they may move too far left and alienate some fiscally liberal, socially moderate “emerging” elements of their coalition.

Maybe most important, if Biden successfully builds the emerging Democratic majority, Republicans will find some way to push back. That’s democracy. Just as Donald Trump found a way through Obama’s supposedly invincible “blue wall,” and Bill Clinton triangulated his way out of the Reagan era, Republicans would eventually find a way around a Biden majority. Is Trump’s surprising resilience with Latino voters already foreshadowing how the GOP might accomplish that?

If on Nov. 3 a winning Biden majority emerges along the lines Judis and Teixeira anticipated, they deserve to take a victory lap — but maybe just one. Then they’d be wise to get to work devising a new strategy for new times ahead.

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