The decisive factor in Hillary Clinton’s victory over Bernie Sanders was her rock-solid support from upscale liberals voting primarily on culture-war issues. White Democrats, in other words, largely voted along class lines.

This was most starkly illustrated when the New York Times published a map of how every precinct in the five boroughs voted in April, with Hillary completely sweeping Brownstone Brooklyn and all of Manhattan save a few lonely precincts on the Lower East Side. It was first seen as early as March 1 in Massachusetts, when Cambridge and its bedroom satellite Lexington put Clinton over the top by a fraction of a percent. And it ensured her consolidating victories throughout the Northeast and finally in California.

The urgent wake-up call that these facts should present to the Democratic leadership is this: While Hillary won the upscale white liberals and minorities who “look like the Democratic Party”—indeed, she lost among registered Democrats only in Vermont and New Hampshire—she still won only 54 percent of the primary vote, and she lost young voters by nearly three-to-one.

The turbulence of this election is best understood as the end of the era that began with the election of 1968, defined by the numerous domestic consequences of the Vietnam War. Published the following year, The Emerging Republican Majority by Kevin Phillips remains the indispensable chronicle of the historical forces that led up to that election, as well as the most breathtakingly accurate forecast of its long-term aftermath. Phillips bluntly described the diminished Democratic Party that would face the Nixon/Reagan supermajority as “the party of the Establishmentarian Northeast and Negro South.” The generation of progressives shaped by this tumult reached its apotheosis in Hillary Clinton’s present campaign.

The presidential contender who set the tone of American liberalism for the epoch that began in 1968 was not a high-minded representative of Cold War liberalism’s better half such as Eugene McCarthy or George McGovern, but Bobby Kennedy, whose campaign represented an odd alliance of the Democratic establishment with such New Left ideologues as Tom Hayden. The politics of Vietnam have obscured the early history of the New Left, which was deeply invested in the idealism of the Great Society—an idealism that Kennedy most effectively channeled.

In his widely praised book The Agony of the American Left, Christopher Lasch diagnosed the fatally limited imagination of this species of leftism. In discussing the lionization of such early-20th-century anarchists as “Big Bill” Haywood and the IWW, Lasch explained that “Haywood’s militancy, his advocacy of violence and sabotage … and his view of radicalism as a movement based on marginal people, all correspond to the anti-intellectual proclivities of the contemporary student left.” Oddly enough, this proved a comfortable fit for Lyndon Johnson’s Great Society, which was directed at such marginal populations as Appalachian coal miners and the black urban poor, as opposed to the more nationally unifying, and thus naturally more popular, programs of the New Deal.

Whatever one’s opinion of Bernie Sanders’s proposals for single-payer health care, tuition-free public college, and a massive reinvestment in infrastructure, they have reemphasized why the New Deal was popular and the Great Society was not. This is a fundamental break from the pattern of missionary progressivism by what in the 1970s was called “the new class” of affluent professionals, typified by the Great Society and over the following decades increasingly conflated with culture-war priorities.

This is the source of the biggest misunderstanding of the Sanders phenomenon by the generation of liberals formed by 1968 and its aftermath. Even older Sanders supporters, hailing from that milieu themselves, have typically assumed that the campaign is merely the latest in a predictable cycle of generational struggle between youthful “egalitarians” and wizened “politicians” (to borrow from the title of the suspiciously timed new book by Sean Wilentz, who is perfectly representative of this conceit as both an ardent Clintonite and nostalgic son of postwar Greenwich Village).

But Phillips provides a clearer insight into what presently roils American liberalism. Perhaps nothing is more striking to the retrospective reader of The Emerging Republican Majority than how completely marginal, if not irrelevant, was the drama of the New Left to the causes of the realignment that led to the Nixon/Reagan supermajority. Phillips recognized what was lost on the political and media elite of the 1960s and ’70s—that the emergence of this supermajority, not the campaigns of Gene McCarthy and Bobby Kennedy, was the real story of 1968.

Much of the political story of the past few years should be understood as the unfolding consequences of a highly analogous situation among the millennial generation. The privileged student radicals of 1968 became the vanguard of the new class, which, despite its electoral marginality, defined American liberalism for the next five decades. Their children, inheriting their values, advanced their cause both in the prestige media and as the loudest, most aggressive voices on elite campuses. Today, that prosperous elite is ever-more isolated from the social and economic devastation that has gripped most of the country.

The overwhelming preference of millennials for Bernie Sanders over Hillary Clinton—and the not-insignificant showing of millennial support for Donald Trump—has thus been a revolt by that generation’s masses against their appointed representatives in prestige media, who were largely responsible for creating the illusions about the mood of the country that have set the tone and underlying assumptions for the Clinton campaign.

This self-satisfied culture-war extremism might have been tolerated by most millennials had it not become the hallmark of open class contempt. But it is no accident that leading corporate liberal publications, from The Atlantic to Slate to New York, traffic in the most unrestrained identity politics, belligerence, and transgender extremism while their mostly young writers have also been the most supportive of Clinton and critical of Sanders.

It may be extremely sobering that Hillary Clinton’s only challenger for the Democratic nomination was both a lifelong independent and a representative of the aging Jewish cohort that is perhaps the last surviving segment of voters with a serious attachment to the class-solidarity appeal of the New Deal Democrats. But it is at least as revealing that only such a man as Bernie Sanders could have rallied the economically hard-pressed youth of America behind a future they could believe in, just as it is now clear that only a human wrecking ball such as Donald Trump could have finally dislodged and buried the rotting corpse of the historic conservative movement.

Many longstanding assumptions about the future of American politics are likely to be exploded over the next several months. Polls have been showing Clinton and Trump running about evenly among millennials, and Nate Cohn of the New York Times has laid out data undermining the assumption of a declining white electorate. Meanwhile, a millennial supermajority that rejects its politically correct mouthpieces, not unlike the boomer supermajority that rejected the New Left, is coming into view.

To be sure, that majority is firmly committed to social and economic policies that are far closer to those of Bernie Sanders than to those of Ronald Reagan. But it is precisely because the liberal culture-war catechism is so totally losing resonance with them—not to mention the slaying of the Reagan policy paradigm by Trump—that the liberal pundit class is invoking that catechism with increasing hysteria. This election will do much to determine how the millennial majority ultimately takes shape.

If Trump wins, the combination of his likely one-term disaster and the shock of a Clinton loss will likely open the way for a lasting generational transformation of the Democratic Party. Unless Trump loses in a landslide, which looks increasingly unlikely, there is no going back to the old order for the Republicans, in which case they could still thwart the emerging Democratic majority of the past decade. Yet the success of the Sanders campaign has made clear that if, as some have suggested, the coming realignment is between the Bloomberg party and the Trump party, the former cannot long survive.

The legacy of the Bernie Sanders campaign will have been to reveal that for the Democrats, no less than the Republicans, the twin legacies of the 1960s—in both the party establishment and its ideological base—are at long last at death’s door.

Jack Ross is the author of The Socialist Party of America: A Complete History and the forthcoming The Strange Death of American Exceptionalism, on the history of the present political moment inspired by the scholarship of Kevin Phillips.