The Democratic Party fight between Hillary Clinton and Bernie Sanders—one likely to extend through the very last primaries if not all the way to the convention—might be compared to the contest between Ronald Reagan and Gerald Ford in 1976. A beloved movement figure is taking on an exhausted yet entrenched establishment, running much better than anyone expected. But like Reagan, even in defeat, Sanders clearly represents the future of the party.

The same anti-establishment story might have once been told about Barack Obama. Yet with the obvious exception of African-American support for the first black president, the belief in Obama as a “transformational” figure turned out to be an elite phenomenon, extending from the political class to the academic left. While then millennial voters did go along with Obama, a far larger, more economically hard-pressed bloc of young voters now seems overwhelmingly with Sanders—a politician who speaks directly to their struggles, giving him an advantage with the working-class Democrats who most resisted Obama in 2008. As that coalition matures in the years ahead, it could easily drift far away from the liberal pieties that have typified the Obama coalition.  

There have been missteps, notably Sanders relying on activists of the so-called “Black Lives Matter” movement to represent him with black voters. Still, despite these blunders, Sanders still stands out as a throwback to former brands of socialist idealism. This, indeed, remains the key to understanding Bernie Sanders.

After growing up in Brooklyn, the cradle of so many activists of his time, Sanders arrived in Vermont in 1964. He had gone north just a short time after graduating from the University of Chicago, where he led a civil rights group. In the wilds of Vermont, he preserved a more radical strain of the original idealism of the civil rights movement—one untainted by black power and the Vietcong, and the subsequent rise of identity politics in mainstream liberalism.

Sanders’s historic socialist identity is seen as anomalous and exotic by the media and worn as a badge of radical daring by supporters. But does his implicit critique of contemporary liberalism qualify as “socialist”? It seems the term has become as useless an ideological descriptor as “liberal” or “conservative.”

Yet one can say that Sanders’s critique fits in squarely with the older liberalism typified by the heyday of Americans for Democratic Action, a group that owed much to the historic American Socialist tradition and represented the best civil libertarian qualities of the Cold War era. Sanders is also squarely in the tradition of the Socialist Party politicians elected in the first half of the 20th century in places as far flung as Milwaukee, Schenectady, Butte, Minneapolis, Reading, and Bridgeport: these places saw candidates who succeeded through delivering on core constituency services and clean government. Like them, Sanders’s first election as mayor of Burlington in 1981 was due to a property tax revolt (and the opportunistic support of the police union). What later earned him up to 70 percent of the statewide vote in Vermont were historically favorable ratings from the NRA and zeal in securing veterans benefits.

Thus it would be a mistake to see Sanders as a mere throwback to the domestic agenda of FDR and Truman. In his unbowed emphasis on blasting away at the plutocratic class, Bernie has been much more like Louisiana populist Huey Long than socialists and progressives such as Norman Thomas or Henry Wallace. And it is equally mistaken to suppose that he would be in the mainstream center-left in Europe—his rise has clearly occurred in parallel with Jeremy Corbyn in Britain’s Labour Party and various anti-EU leftist parties on the continent.

This reproach from the distant past confronts an American liberalism in which Hillary Clinton represents the once settled principles of the post-Cold War era: deference to the financial elite, an activist foreign policy, a progressive culture war offensive. The Clintonian approach, which largely writes off the white working class, is essentially the platform first forged by the centrist Democratic Leadership Council in the 1980s. But a funny thing happened on Hillary’s way to the White House: suddenly, her party and the country are more concerned with economic inequality, criminal justice reform, climate change, and avoiding new wars in the Middle East.

It was not necessarily Sanders’s intention to provoke a debate about the future of liberalism, and he has not aggressively pursued it. Critics frequently call out his reliance on vague talk of popular mobilization (“a political revolution”) when asked how he would pass his agenda against Republican opposition. Left unacknowledged is how much the politics of a Democratic primary constrain him from making a clearer argument, a forceful critique of the party’s establishment and its priorities.

Yet despite the challenges Sanders faces, it’s hard to see how the anti-establishment Left could have found a better candidate. In retrospect, the once sought after progressive Elizabeth Warren would have fared poorly as Clinton’s challenger. Not only is Sanders’s record on foreign policy and civil liberties far superior, but Warren is far more inclined to indulge in fighting the culture war from the Left. On at least two issues Sanders has taken the bolder economic populist position opposed by Warren: for shutting down the Export-Import Bank and for Rand Paul’s Audit the Fed bill. By the same token, Sanders has been better able to make this critique in a Democratic primary than the once-promising Jim Webb ever could have. In short, no other candidate could have made such strides in restoring the party’s working class appeal while maintaining credibility with the Democratic base.

Alas, it may not be enough this year, if only because of the limitations that would have confronted any challenge to the current Democratic coalition, a situation now exacerbated by white working class defections to Donald Trump. A Clinton-Trump race, and a Trump victory, would only extend the volatility of the American electorate that has defined the past decade. Still, it would probably take far less pressure than a Trump presidency to completely upend the Democratic establishment, creating a new coalition as inconceivable and offensive to the party of Obama as Trump is to the party of Bush. Indeed, Sanders has gone farther in his Democratic insurgency than Ron Paul was able to in the GOP. Nor can a Sanders victory yet be ruled out—momentum may quickly shift against Clinton as the reality sinks in of what a Clinton-Trump race would mean.

Either way, stranger things have happened, not least in this election, than a white-haired secular Jew with a thick Brooklyn accent becoming the voice of the silent majority. Nearly as strange as what almost happened in 1976 before coming to fruition in 1980—a B-list Hollywood actor upending what was once left of the centrist, Rockefeller Republican coalition. A Democratic establishment that underestimates Sanders forgets that powerful movements are often headed by the most unexpected of leaders.

Jack Ross is the author of The Socialist Party of America: A Complete History. He is currently at work on a book about the demise of American exceptionalism.