Jennifer Delton is the Douglas Family Chair in American culture, history, and literary and interdisciplinary studies at Skidmore College. She is the author of, most recently, 'Rethinking the 1950s: How Anticommunism and the Cold War Made America Liberal."

Sen. Bernie Sanders may cite the New Deal as his preferred model, but its politics were based on social homogeneity and a manufacturing economy — neither of which still exists in the United States. (Drew Angerer/Getty Images)

For the first time in a generation, the American left seems poised to exert real influence on Democratic politics. But the 21st-century left has been plagued by the persistent fantasy that it represents the return of the Old Left of the 1930s, a purer left that existed before identity politics complicated genuine class alliances.

Nonsense.

To be clear, the left — as represented by the Sanders movement — is perfectly able to attract women and people of color to its class-based vision of the future. Although highly educated white men are typically its most passionate spokesmen, its message nonetheless appeals to people of all genders, races and sexualities who have gotten the short end of the stick in today’s hyper-unequal society.

Yet the problem with the rising left is that it thinks working-class people in a highly diverse society will be able to put aside other allegiances such as race and gender to challenge a neoliberal economy that has, arguably, been pretty friendly to identity politics. There is simply no historical precedent for this kind of alliance, least of all in the New Deal, which Sanders holds up as his social-democratic model. The allegedly class-based politics of the New Deal era depended on social homogeneity and a manufacturing-based economy — neither of which exist today.

Immigration restrictions enacted during the 1920s provided the millions of immigrants who had entered the country at the turn of the century a chance to assimilate. They also tightened the labor market, which raised wages and provided workers a little more leverage vis a vis their employers.

People who might identify by ethnicity at the local level were finally able to organize as workers at a national level, becoming a game-changing constituency for the Democratic Party. New Deal policies transformed this group, once the epitome of the immigrant hordes, into a white, suburban, Democratic majority. New Deal Democrats achieved consensus because the majority of their voting population was similar — much as socialism works in mostly homogeneous Scandinavian countries today.

In the 1930s, New Deal liberals took over a Democratic Party dominated by white Southerners who wouldn’t dream of voting for the party of Lincoln. Southern politicians were happy to accept New Deal largesse in terms of rural electrification, cotton subsidies and economic development, as long as it didn’t disrupt Jim Crow segregation and black disfranchisement. Liberals accommodated their wishes, selling out African Americans in the process, and in return were able to count on “the Solid South” in elections.

This arrangement strained during the 1940s and 1950s, as civil rights issues grew in importance, most notably with South Carolina Gov. Strom Thurmond bolting the Democratic Party in 1948 to run for president as an independent “Dixiecrat.” President Lyndon Johnson doomed the New Deal coalition once and for all when he signed the Civil Rights Act of 1964 and the Voting Rights Act of 1965, which began the long process of creating a more integrated, inclusive, diverse society. White Southerners, appalled by this vision, ditched the Democratic Party.

Unions — which represented the “class” part of New Deal politics — reflected the white male homogeneity that marked the New Deal and post-World War II eras. Unions traditionally sought to restrict labor markets, and thus opposed immigration and excluded blacks and women. They were, after all, brotherhoods. This changed with the large industrial unions of the CIO in the 1930s, whose leaders grasped that their power depended on including minority racial groups. But many unions were nonetheless torn apart over civil rights and affirmative action. A substantial number of union voters defected from the Democratic Party over this issue, as well as abortion, women’s rights and other liberal causes that emerged in the 1960s and 1970s and challenged the hierarchies long accepted by these unionists.

Unions, moreover, depended on a manufacturing-based economy — their power rested on deals New Dealers negotiated with manufacturing interests. When the financial, real estate and high-tech sectors replaced manufacturing as the basis of the U.S. economy in the late 1980s, “new Democrats,” or “neoliberals,” such as Gary Hart, Al Gore, Bill Bradley and Bill Clinton, abandoned declining industrial sectors and the welfare state in favor of new industries, new social movements and a new less-government-centered approach to addressing societal problems.

The new more diverse Democratic coalition of minority groups, working women and highly educated, pro-immigration professional and creative types is as tied to a heterogeneous neoliberal economy as the old unions were to manufacturing. Whereas the labor movement had provided the old Democratic coalition with its animating vision, the new Democratic coalition’s moral, progressive cause is centered on diversity, opportunity and inclusion of once-excluded groups. Much as the labor movement went hand in hand with a government-regulated manufacturing economy, diversity is accordant with the deregulated, free-trade, global economy of neoliberalism.

Indeed, some of the biggest defenders of affirmative action and diversity are large multinational corporations. Even in the 1980s, they opposed conservatives’ attempts to restrict affirmative action and immigration, policies they depended on to put them in compliance with anti-discrimination laws, foster good public relations and secure the most talented and globally competitive labor force possible. Corporations and investors understand that their best customers — the highly educated, highly paid consumers of financial services, luxury autos, fancy schools, artisan craft beers, green living and wellness products — are also most sensitive to diversity issues. Hence the quick corporate boycotts against North Carolina’s bathroom laws.

The left derides corporate diversity efforts as ineffectual and inauthentic. They point out that the new industries are riddled with sexual harassment, race and gender discrimination, and lack of something called “representation.” But at least the leaders of those industries are concerned about these problems and not in open rebellion against a diverse society. Centrist Democrats work to hold these corporations accountable for their diversity shortcomings, which they can only do if they are fundamentally supportive of their economic interests — much as New Dealers supported the manufacturing interests on which the labor movement depended for jobs and power.

Historically, “class politics” has depended on a certain kind of solidarity and unity, in which race and ethnicity take a back seat to the class agenda, the argument being that capitalists stoked racial and ethnic differences precisely to divide the working class. But today, identity politics that openly emphasize those differences thrive as various identity groups lay claim to recognition and remuneration. Identity is fluid, multivalent, self-chosen and completely compatible with the individualistic, unregulated, innovation-oriented, forward-looking, globalizing economy of neoliberalism.

Perhaps most problematically, the liberal identity politics of our ultra-heterogeneous historical moment demand not only accommodation to myriad kinds of “difference,” but also the acceptance of new social rules, sometimes called “political correctness,” which has alienated erstwhile class allies, even as neoliberal elites, especially in the areas of higher education, marketing and the arts, have been remarkably open to these demands.

These tensions, of course, are easily exploitable and play right into the hands of the right’s provocateurs, men such as Richard Spencer and Milo Yiannopoulos, who have mainstreamed a once-taboo racial nationalism. When Trump supporters extol their president’s honesty, they mean that he has the gumption to flout political correctness. There are parts of the left that recognize “political correctness” as part of the liberal elite’s domain and have held it up for mockery, but they don’t address the pull of racial solidarity at a time, for instance, when a movement like Black Lives Matter unites blacks of all classes, but is alienating to many lower- and working-class whites.

So while a return to “class politics” sounds like a tantalizing pathway back to political power in this age of extreme economic inequality, the New Deal actually provides no road map here. To achieve this goal, the left must devise an entirely new type of class politics that manages to embrace today’s identity politics without fracturing over cultural, racial and gender issues — a task that might be impossible.