As they enter the fall campaign season, Democrats have numerous reasons to be optimistic, if not giddy. Their Republican opponents have become widely unpopular due to a prolonged war and a weak economy. Meanwhile the rising demographic groups in America, the millennial generation and Latinos, are shifting heavily to Democrats.

But this Democratic ascendancy is by no means guaranteed for the long run. The changing nature of the party casts its future in doubt, particularly after 2008. Much of this has to do with how the party’s base has shifted, and where that base may lead it over the coming decades. In other words, to borrow roughly from Franklin Roosevelt, the only thing the Democrats have to fear is themselves.

The Rise of the New Class
The swing to the Democrats in recent years reflects in part the natural rhythm of American politics. The Democrats declined in the 1970s in part because the country recoiled from the failures of the Great Society. The bright Democratic prospects of 2008 are similarly a reaction to the Bush years.

Yet today’s Democratic revival represents something far more profound. Rather than a shift to the “middle,” the current Democratic tide reflects a long-term secular shift in the composition of our economy and our class structure.

The only thing the Democrats have to fear is themselves.

Americans may dislike the term class, but it has been an essential part of our political history. And for most of our history, Democrats represented the middle and working classes, dating at least back to the days of Andrew Jackson. Under William Jennings Bryan, the Democratic Party cast itself as largely the voice of the small farmer and the working and middle classes. Franklin Roosevelt, Harry Truman, and even Bill Clinton maintained this tradition.

Yet over the past two decades, and particularly the last few years, the party’s base has shifted decisively in both demographic and geographic terms. Increasingly, the core Democratic constituency—and, even more so, the base of Senator Barack Obama’s campaign—consists not of working- and middle-class whites but of African-Americans and a rising new class of affluent, well-educated professionals.

This second group, largely white but certainly spread across racial groups, has begun to supplant the old working- and middle-class base of the party. For the most part it differs from the old middle class of shopkeepers, skilled industrial workers, and small farmers, constituencies that have struggled as the economy has globalized and been transformed by the information revolution.

In contrast, the new class has thrived and expanded. Democratic activist Ruy Teixeira has made this case convincingly, pointing out that almost one-third of adults now have college degrees, up from 5 percent during the heart of the New Deal. This group has thrived during the century’s economic transformation, as their wages have risen 22 percent since 1979—28 percent for those with graduate degrees—even as wages have fallen for those with only high school degrees.

They have become the linchpin of a mass affluent class whose influence and geographic spread have been growing as that of the less educated has waned. A half century ago the highly educated component of the population represented a small constituency concentrated in a few places like New York, Cambridge, and Berkeley. Today their influence can be felt not only in major cities, but in wealthy suburbs, college towns, and even in some rural havens.

Even though many of these voters have benefited from Republican economic policies, they have become ever more Democratic. Academia and the news media constitute the nerve center of the new class. Indeed, academic professionals were one of the largest sources of contributions to John Kerry’s 2004 presidential campaign.

Our greatest liberal cities are becoming bastions of the stratified neo-Victorian class structure that economic liberals purportedly despise.

But this leftward shift extends well beyond academia. In the mid-1990s high-income voters preferred Republicans by 20 percentage points; in 2008 they appear to be decisively favoring the Democrats. Already, the most affluent districts in the country—from Silicon Valley and Manhattan to Madison and the Washington suburbs to west Los Angeles—are also among the most solidly Democrat.

The shift among the affluent has also had an impact on the financing of campaigns. Tied to burgeoning information age sectors, notably finance, entertainment, and technology, the post-industrial new class has shown itself to have deeper pockets than the old Republican establishment. Democratic candidates by this spring had raised 70 percent more than their GOP rivals.

Much of this has come in relatively small contributions, but it also reflects a significant shift to the Democrats among such traditionally Republican constituencies as Wall Street. As late as 2004, the financial industry contributed more to Republicans than Democrats; this year Democrats are ahead by a roughly two to one margin. Together Senator Hillary Clinton and Senator Obama have raised five times the amount garnered by Senator John McCain.

Inequality and the Post-Industrial Hierophants
At the highest level of this new class stand the reigning elites of the Democratic Party—top university administrators and academics, venture capitalists, media and Internet barons, the “stars” of Hollywood, and the cutting-edge firms on Wall Street. These figures represent precisely what Daniel Bell called the “hierophants” who define the post-industrial age, its mysteries, and its values.

These hierophants—such as David Geffen or top executives at Google—differ both culturally and stylistically from the super-rich who supported conservatives in the past. They are as likely to dress in blue jeans as expensive blue suits, belong to the Sierra Club instead of the country club, or believe in holistic medicine more than the Holy Gospels.

Their recent experience as entrepreneurs differentiates them from traditional power elites. Unlike the corporate bosses of yesteryear, their expertise does not depend on their ability to produce mass goods and control or cajole large numbers of lesser skilled white-collar and blue-collar workers. Instead, their wealth derives from the successful manipulation of images, ideas, and trends; most of the workforce they manage consists of people with widely similar educations and cultural persuasions. Their main experience with the less educated lies with immigrant employees who watch over their properties, pets, and, in some cases, offspring.

Many green-minded Dems believe suburban living is a major contributor to global warming. Their war against suburbia may threaten middle-class Americans.

As liberals, of course, the new class and its elite occasionally complain about the growing gap between the rich and everyone else. Yet contemporary liberalism’s strongest bastions lie in cities and metropolitan regions such as New York, Los Angeles, and San Francisco where, according to a recent Brookings Institution survey, inequality is the most pronounced. All these places have been losing middle-class families who no longer can afford to live there.

In this way our greatest liberal cities are becoming centers of the stratified neo-Victorian class structure that economic liberals purportedly despise. One statistic that speaks volumes: the San Francisco, Washington, New York, and Boston regions all boast the highest percentage among major U.S. metros of people who earn money in classic plutocratic fashion: from stocks, bonds, and rents.

These factors may make it difficult for Democrats to govern as the party of what used to be called “economic justice,” even given the presence of a widening gap between the rich and the middle class. It’s revealing that, rather than express outrage at the huge payouts to the Wall Street elite, Democrats generally prefer to demonize oil company executives, whose pay, if more than generous, pales in comparison to that earned by the traders and speculators.

Even for politicians, it must seem somewhat of a stretch to troll for dollars in the luxury condos of Manhattan and Chicago one day, and play class warfare the next. Once in power, it’s unlikely Democrats will do much more than talk about curbing the excesses of the rich. Already, one of their leading lights, New York Senator Charles Schumer, has emerged as chief defender of the hedge-fund industry, an emerging bulwark of Democratic support.

If he becomes president, you can’t expect much negativism about rapacious hedge-fund managers from Senator Obama, who emerged as the early favorite of highly compensated, younger Wall Street executives. “Mr. Obama might be struggling with the blue collar vote in Pennsylvania,” noted New York Times Wall Street maven Andrew Ross Sorkin, “but he has nailed the hedge-fund vote.”

The Obamaization of the Democratic Party
The origins of the new Democratic Party can be traced to at least the 1960s, starting with the nesting of intellectuals such as Arthur Schlesinger in the Kennedy administration. Yet even then, the party’s base remained very much with the white working class, urban ethnics, and a smattering of rural populists. The Republicans remained very much the predominant party of big money and corporate power.

The Democrats who succeeded in the largely conservative epoch after 1968 were those who figured out how to win over middle- and working-class Americans. This group included not only urban voters but people in small towns and the vast, largely nondescript suburbs that grew around the major cities. Jimmy Carter got enough of their support to defeat Gerald Ford in 1976; Bill Clinton did it twice, in 1992 and 1996.

Although the Clintons also garnered support from the new elites, they never forgot to compete in the suburbs and small towns. Senator Clinton’s best moments as a candidate in the Democratic primaries came as she won over these voters in places like central Pennsylvania, Ohio, and West Virginia. The problem for the former First Lady lay in the fact that the balance of power in the party had shifted decisively—both economically and electorally—away from these voters and toward the new class. Being the favorite of the small-town coffee shops and steel plants had been enough for Bill Clinton to defeat the likes of Paul Tsongas. Today it no longer guarantees the nomination.

Once Senator Obama gained almost total allegiance from African-Americans, the Clintonian alliance was spent and a new, reformulated Democratic Party was born. This new party has four critical constituencies: the post-industrial new class, African-Americans, young “net-roots” activists, and, finally, the elites of the information age.

The ‘Green’ Politics of the New Class
The Democrats will be running against a far weaker Republican Party than they did in the 1990s. For Senator Obama, the biggest danger comes not from the right but from his own base, whose predilections may over time limit his appeal and stunt the party’s gains.

Like all classes, the new post-industrial constituency and its leaders have their own agenda. They may not be above pandering to the traditional working and middle class, but they do not have their same priorities. Fundamentally, the Obamaized Democratic Party is less about bread-and-butter issues—trade, energy prices, and competitiveness—than that of the Clintons.

Throughout the primaries, Senator Obama did best with voters, outside of African-Americans, who were themselves doing relatively well. Generally speaking, the wealthier the constituency, the better he did. Also, since the new class for the most part has little connection to the military, they are less likely to be overly concerned with national security issues (something Senator Clinton, in particular, worked hard to develop credibility on).

In contrast, Obama Democrats tend to be energized either by an antiwar message or by cultural issues—abortion, affirmative action, gay rights. Perhaps more critical for many of these voters, and interests, may be the environmental issue. Although this has not been a major topic in the primaries, the key Obama constituency among educated young voters tends to be the most fervent on issues such as global warming.

How to deal with the environment may be a critical area of conflict between the interests of the traditional middle class and the postindustrial new class. By its very nature, people working in the key institutions of the information economy—software firms, entertainment, Wall Street—are not unduly harmed by attempts to regulate reduction of carbon emissions.

Even for politicians, it must seem incongruous to troll for dollars in the luxury condos of Manhattan and Chicago one day, and play class warfare the next.

In contrast, workers in transportation, wholesaling, and manufacturing sit on the carbon front lines. Radical steps to curb carbon emissions, particularly if not imposed on major competitors like India, China, and Brazil, will hurt miners in Montana, oil workers in Texas, factory workers in Michigan, and dockworkers in California far more than university professors, San Francisco graphic artists, and New York investment bankers.

What’s more, most middle- and working-class voters cannot afford to buy indulgences in the form of “offsets,” such as purchasing parcels of rain forests. Indeed, in some ways, the current approach on carbon emissions parallels how liberals in the 1960s shifted the burden of achieving long-overdue racial integration by imposing busing or affirmative action plans on primarily working- and middle-class Americans.

Perhaps even more threatening to middle-class Americans may be attempts by green-minded Democrats to wage war on suburbia, home to the majority of Americans. Many greens are convinced that suburban living has been a major contributor to global warming and needs to be curbed.

Academics, the coastal media, and big urban developers have long recoiled from suburbia’s cultural and aesthetic failings; the new political paradigm might well be their opportunity finally to do something about it. Legislation and legal actions coming out of places like California—led by Attorney General Jerry Brown—seek to cajole Americans out of family-friendly suburbs. “We have to get the people from the suburbs to start coming back,” Brown insists.

None of this should upset the core constituencies of the new Democratic Party, who tend to live in dense, urban zones like Manhattan, Boston, and San Francisco. They will continue to enjoy the best of urban life while also indulging their somewhat less carbon-friendly vacation homes and coastal condos.

Rovian Democrats?
The new class’s disdain for suburbia and middle-class lifestyles could produce a new version of the cultural warfare exercised by the Republicans in recent years. Under the political strategy developed by Karl Rove, millions of Americans—gays, singles, ex-hippies, non-Christians, urbanites, single parents—often saw themselves as ostracized by a party that embraced, at least publicly, what felt to them like a vaguely menacing set of “family values.” In the end, this exclusionary approach drove millions of Americans to the Democrats; cultural shifts, such as greater tolerance for gay rights among the young, increasingly have worked against the Rovian strategy.

Now the Democrats could soon be in danger of duplicating the Republican mistakes. The Clintons won by “triangulation” and appealing to the broad range of middle-class voters. But Obama’s Democrats could become the mirror image of Rove’s Republicans, extolling the superiority of their base and its values over those of other, less “enlightened” populations.

The post-industrial new class has shown itself to have deeper pockets than the old Republican establishment.

This becomes a real possibility in an administration staffed with people shaped by sophisticates from Chicago, Manhattan, Austin, San Francisco, and Boston. These are likely individuals who do agree with Senator Obama’s unfortunate comments about “bitter” small-town residents, guns, and God. They could well see it as their duty to stamp out suburban sprawl and force other Americans to live, as they do, like good urbanites, even if they ignore the fact that most, particularly those with children, lack the wherewithal to do so comfortably.

This conflict could come to the fore very quickly, as Democrats generally believe in using government to achieve goals more fully than their political rivals do. Republicans are often far too willing to repress individual rights for security reasons but generally have proved less eager in reality to tell people how to live on a day-to-day basis. There may be no place in America, for example, where people are more cajoled in their daily behaviors than San Francisco.

There are many things government should do short of telling people where to live, what kind of house to buy, which store to patronize, and who should be preferred for a job. For example, after years of neglect, there is a critical need for new investment in the nation’s economic infrastructure, transportation network, and broken system of trade education, as well as massive incentives for new energy development and scientific research.

This approach would address the longterm needs of the working and middle class. This return to a basics-oriented liberal politics would help Democrats among the very disaffected blue-collar and older voters now flirting with the idea of supporting the lone-wolf candidacy of John McCain.

Ultimately this is Senator Obama’s choice: follow a broad winning strategy based on traditional middle class-oriented policies, or adopt the ideological and economic predilections of his core base. If he does the latter, many Americans may find themselves alarmed by the Democrats’ resurgence.

Joel Kotkin is a presidential fellow at Chapman University and author of “The City: A Global History.” He is finishing a book on the American future.

Illustration by Robert Grossman.