Pundits keep reminding us that the two men who won New Hampshire, Donald Trump and Bernie Sanders, are both “outsiders.” But that doesn’t mean much. George Wallace and George McGovern were both outsiders, too. While the Trump and Sanders campaigns both represent insurgencies against party elites, they represent insurgencies aimed at taking America in radically different directions. One way of understanding those different directions is through American exceptionalism. Sanders voters want to make America more like the rest of the world. Trump voters want to keep America a nation apart.

American exceptionalism has meant different things at different historical periods. But today, it generally denotes Americans’ peculiar faith in God, flag, and free market—a religiosity, a nationalism, and a rejection of socialism and class-consciousness that distinguishes the United States from other advanced democracies. The Sanders campaign represents an assault on all three. From H.G. Wells to Karl Marx, foreign observers have long fingered America’s lack of socialism as a key characteristic distinguishing it from Europe. But Sanders is a democratic socialist; he doesn’t run from the term. And neither do his backers. In a January poll of likely caucusgoers in Iowa, The Washington Post reported that more Democrats called themselves “socialists” than “capitalists.” Sanders’s socialism is especially popular among the young. A 2011 Pew Research Survey found that while Americans 65 and older favored capitalism over socialism by 39 points, Americans under 30 favored socialism.

But their comfort with socialism only hints at the ways Sanders supporters are challenging long-established notions of what sets America apart. Chroniclers of American exceptionalism have long argued that the reason Americans eschew socialism is because they don’t see themselves as members of a fixed class. Instead, they see their economic position as fluid. As Marx himself said, “Though classes, indeed, already exist [in the United States], they have not yet become fixed, but continually change and interchange their elements in a constant state of flux.”

Young Americans, the population to whom Sanders appeals most, don’t believe that. Polls show that they are far more likely than their elders to believe that the rich got that way because they “know the right people or were born into wealthy families” than because “of their own hard work, ambition and education.” Older Americans overwhelmingly identify themselves as “haves.” A majority of younger Americans, by contrast, call themselves “have nots.” Older Americans overwhelmingly call themselves members of the “middle class.” Young Americans are almost as likely to call themselves “lower class.”

In embracing Sanders’s socialism and class-consciousness, young Americans are making America more like Europe. In 2003, according to Pew, Americans were 17 points more likely than Italians and 16 points more likely than Brits to say, the “free enterprise system and free market economy is the best system on which to base the future of the world.” By 2010, that gap had virtually disappeared. In 2002, Americans were 16 points less likely than Brits to say, “Success in life is determined by outside forces.” By 2011, the gap was down to five points.

If Sanders’s economic views challenge American exceptionalism, so do his religious ones. Not long ago, it would have been hard to imagine a leading presidential candidate declaring, without embarrassment, “I am not actively involved with organized religion.” After all, America’s passionate religiosity is another characteristic that supposedly sets the United States apart from the rest of the developed world. But here, too, Sanders embodies a shift manifesting itself among the young. According to a 2012 study by the sociologists Michael Hout, Claude Fischer, and Mark Chaves, 32 percent of Americans aged 18 to 24 expressed no religious affiliation. That’s more than four times the rate of religious non-affiliation among Americans over the age of 75. Sanders is succeeding as a secular candidate because the young are making America—and especially the Democratic Party—more like Europe. According to a 2011 Pew study, Americans over the age of 50 were 23 points more likely than Germans of the same age to say it is “necessary to believe in God to be moral.” When Pew compared Americans and Germans under the age of 30, however, the gap shrunk to only eight points.

Finally, Sanders eschews the flag-waving, “We’re number one”-style nationalism that also supposedly sets the United States apart. He does not wear the stars and stripes on his lapel, and his supporters would groan if he did. He’s patriotic but not nationalistic. Unlike even Barack Obama, he doesn’t go around saying America is the greatest country in the world. Originally, commentators thought this might sink him. “I can hear the Republican attack ad right now,” declared George Stephanopoulos early in the campaign. “He wants America to look more like Scandinavia.” But for Sanders, that’s no insult. He happily admits that America isn’t always best. “That’s right. That’s right,” he told Stephanopoulos. “And what’s wrong with that? What’s wrong when you have more income and wealth equality? What’s wrong, when they have a stronger middle class in many ways than we do?

Here again, Sanders can successfully challenge American exceptionalism because America’s young are challenging it. Fewer than one in three Millennials, compared with almost three in four Americans over the age of 75, say the United States is the greatest country in world. Americans over the age of 50 are far more likely than Germans, Brits, and Spaniards their own age to say, “Our culture is superior to others.” Americans under the age of 30, by contrast, are actually less likely than their Western European counterparts to say so. Young Americans are embracing Bernie for the same reason they’ve embraced soccer. And for the same reason they’d likely embrace the metric system. Unlike many of their elders, they simply don’t believe that because America has always done something differently than the rest of the world, that makes it right.

All of which helps explain why those elders are more likely to vote Republican. Within the GOP field, it’s a virtual given that part of what makes America great is its distinctiveness. Marco Rubio warns (and warns and warns) that, “Barack Obama is undertaking a systematic effort to change this country, to make America more like the rest of the world.” His response to Sanders is: “If you want to live in a socialist country, move. I want to live in America.”

But Trump’s defense of American separateness is the most extreme. His entire campaign is built around the idea that foreign influences are infecting the United States. He wants to build a wall to keep out undocumented Mexicans. He wants to temporarily bar entry by Muslims. He has accused President Obama of not being born in the United States and suggested that Ted Cruz may not being eligible to be president because he was born in Canada. “The U.S.,” he declared upon announcing his presidential campaign, “has become a dumping ground for everybody else’s problems.”

Trump’s supporters like the fact that he’s rich, blunt, and hasn’t spent his life in politics. But his pledges to keep the rest of the world at bay are core to his appeal. In New Hampshire, Trump lost to John Kasich by 12 points among voters who oppose banning Muslims from entering the United States. But among voters who favor the ban, Trump beat him by 33 points. Trump and Kasich tied among voters who believe undocumented immigrants should have a path to legalization. But among voters who want to deport the undocumented, Trump won by 43 points.

The one area where Sanders might appear to share Trump’s desire to keep America apart would be trade. The billionaire Republican proposes tariffs against countries like China and Japan that “rip America off,” and Sanders, for his part, has opposed every trade deal since NAFTA. As a result, it’s possible, especially as the presidential campaign moves to Midwestern industrial states hard hit by global competition, that Sanders could win voters who might otherwise support Trump.

But if you look at Sanders’s ultimate vision for the global economy, it’s not separatist at all. He doesn’t oppose international trade; he just wants to regulate it. He supports “a progressive alternative to corporate globalism-based on global labor rights, environmental protections, sustainable development, democratization and international institutions to counter uncontrolled deflations and the race to the bottom.” This “new architecture” for the global economy may seem far-fetched. But it helps explain why Sanders’s supporters oppose trade deals without opposing immigration. They’re happy for America to integrate itself more into the rest of the world, so long as they believe that integration increases justice for the poor and working class. Sanders, after all, is a socialist. And socialists have historically challenged international capitalism not by retreating behind borders but by forging links with workers of different countries and thus building an internationalism of their own.

Despite their victories in New Hampshire, it’s still unlikely either Sanders or Trump will win their party’s nomination. But their success says something profound about the shifting identities of the two political parties. While grassroots Democrats and Republicans remain divided over the size of government, increasingly, what divides them even more is American exceptionalism. In ways that would have been unthinkable in the mid-20th century, the boundaries between American and non-American identity are breaking down. Powered by America’s secular, class-conscious, transnational young people, Democrats are embracing an Americanism that is less distinct than ever before from the rest of the world. And the more Democrats do, the more likely it is that future Trumps will rise.