This article is from the archive of our partner National Journal

Political power in America today is divided like a layer cake that is blue at the top and bottom and red everywhere in between.

Democrats have built two electoral strongholds. At the pinnacle, they have won the popular vote in five of the past six presidential elections and carried at least the same 18 states each time—the most states the party has ever won in six consecutive races. At the base, Democrats now hold the mayor’s office in most big cities and generate huge presidential margins from those densely populated areas.

But in between, as political analysts Sean Trende and David Byler have noted, Republicans control more than three-fifths of the governorships and the most state legislative seats since the 1920s. It has been that long since Republicans held so many seats in the House of Representatives; the party’s 54 U.S. senators nearly equals its best showing since then.

Among the many virtues of America Ascendant, the provocative book published this week by veteran Democratic pollster Stanley B. Greenberg, is its recognition that these contrasting strengths each flow from the same current: an overlapping generational, racial, and geographical realignment that has produced mirror-image partisan coalitions that are antithetical in their values and priorities—but are almost exactly equal in size.

Greenberg makes clear he believes that, unless Republicans make peace with social changes they are now resisting, the underlying demographic and cultural trends reshaping American life will increasingly tilt the electoral balance toward Democrats. But he’s also clear-eyed about the obstacles Democrats face in transmuting these cultural shifts into a true governing majority. Democrats will find more to cheer in this sweeping and deeply informed book than Republicans will, but it offers insights neither side can ignore.

Like other analysts, Greenberg argues that the transition to an information-age economy, growing racial diversity, and changes in gender roles and family structure are shaking American society today as powerfully as industrialization, urbanization, and mass immigration did in the late 19th century. Today’s changes, he writes, are generating opportunity and disruption in equal measure: “While these revolutions are tilting America’s trajectory upward, they are also producing sudden, sweeping and accelerating social changes, evident in the decline of the traditional family and the struggles of working-class women and men.”

Amid this turbulence, Democrats have built a heavily urbanized coalition of minorities, the millennial generation, and college-educated, single, and secular whites (especially women), who mostly welcome what Greenberg calls America’s “racially blended, multinational, multilingual, religiously pluralistic society.” Each of those groups is growing within the electorate, which means that if Democrats can maintain their loyalty, they will provide the party a widening edge, especially in presidential races.

At the same time, Republicans are amassing enormous margins from groups who are the most uneasy about these cultural changes: older, blue-collar, nonurban, and religious whites. By fiercely resisting these trends—on issues from immigration to gay marriage—Republicans have established unchallenged control over 20 states Greenberg describes as the “conservative heartland.” But in his most provocative argument, Greenberg maintains that this very success threatens the GOP with a “death spiral” in presidential elections because “the battle for traditional values … only further alienate[s] the Republicans from the burgeoning new electorate.”

Greenberg sees a structural problem for Democrats, too. Their dominance of culturally liberal population centers allows them to win presidential (and most municipal) races. But they can’t sufficiently expand their geographical reach in congressional and state elections without developing more compelling solutions to the economic strains battering families, particularly those without advanced education.

That’s far easier said than done. Greenberg prescribes an agenda of economic populism, political reform, and help for working parents. But white working-class suspicion of Democratic priorities runs deep. While party strategists like Greenberg long hoped that health reform would convince working-class whites that government could benefit them, polls show they mostly view it as a welfare program for the poor. The Democrats’ consistent movement toward the left on social issues compounds their problems in more culturally conservative (and predominantly white) exurban and rural communities. The combined result is a systemic Democratic decline beyond the boundaries of cosmopolitan urban centers that now tilts both the House of Representatives and state legislatures, even in many swing states, toward the GOP.

As long as Republicans resist America’s demographic transformation, Greenberg is right to believe that Democrats will remain favored in most presidential elections. And he’s also right that, just as in the late 19th century, the policy innovations that cities are pursuing (on issues like universal preschool) will provide a policy model for Democratic presidents to come.

But even if Democrats can hold the White House in 2016, they face a long, uncertain climb to reacquire enough power in Congress and the states to broadly expand the ideas they are incubating in the cities. As the nation careens through the tumultuous cultural and economic transitions Greenberg so deftly describes, it seems more likely to continue to divide authority than to empower either party to impose its preferred vision of America’s next chapter.

This article is from the archive of our partner National Journal.

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