For almost 60 years, two generations have held the American presidency. The Greatest Generation—born in the early 20th century—first won the White House in 1960, when John F. Kennedy was 43. Baby Boomers—born after World War II—took over in 1992, when Bill Clinton was 46. By this precedent, Generation X was ripe for a president in 2016. Three of the early Republican front-runners—Marco Rubio, Ted Cruz, and Scott Walker—would have entered the Oval Office in their 40s. But each faltered, and America replaced Barack Obama, a young Boomer, with Donald Trump, an older Boomer. Rather than choose a generational successor, America elected a candidate 15 years older than the president he replaced, the largest such jump in American history.

Now Gen Xers have another shot. Many of the 2020 presidential contenders who sparked early enthusiasm—Cory Booker, Beto O’Rourke, Julián Castro, and Kamala Harris—were born between the mid-1960s and 1980, the span that defines Generation X. (Harris, born in 1964, is on its cusp.) But as of midsummer, with the exception of Harris, they were all below 5 percent in national polls. The result is a top tier of candidates that, in addition to Harris, includes three who are roughly Trump’s age—Joe Biden, Bernie Sanders, and Elizabeth Warren—and Pete Buttigieg, a Millennial.

If a Gen Xer doesn’t win in 2020, there will be another chance in 2024. But by that time the field may be crowded with Millennials—born from 1981 to 1996—whose ranks include Buttigieg, Alexandria Ocasio-Cortez, and rising Republican stars such as Representatives Dan Crenshaw and Matt Gaetz. Sandwiched between two larger and more politically consequential generations—Boomers and Millennials—Generation X may never produce a president at all.

This electoral weakness isn’t coincidental. It reflects an ideological problem. Rubio, Cruz, Walker, Booker, O’Rourke, Castro, and Harris all entered adulthood between the Reagan and Clinton eras, and launched their political careers around the turn of the millennium. That means they likely began forming their political beliefs at a time when the Republican Party had a strong pro-immigration wing and leading Democrats embraced free trade, tough anti-crime policies, and charter schools. Then, as they came closer to running for president, an ideological earthquake hit.

Since 2016, the Democratic Party has lurched left. Nativists have taken over the GOP. Among activists in both parties, views that were once mainstream are now widely reviled. Gen X politicians have responded by either downplaying or repudiating their prior positions. That’s unfortunate, because not everything that leading Republicans and Democrats believed before the parties reinvented themselves has been proved wrong. Gen X politicians could help check the hubris of the present—if only they would now defend what they once believed.

According to social scientists, events that occur while people are entering adulthood have a disproportionate influence on their political views. That doesn’t mean everyone who comes of age around the same time interprets those events in the same way. Rather, particular eras create particular intragenerational arguments. Think about the way Baby Boomers have spent their political careers debating the legacy of the Vietnam War.

The fight that has defined Generation X is between conservatives who came of age idolizing Ronald Reagan and liberals who came of age embracing Bill Clinton’s response to him. As ideological children of Reagan, who granted legal status to nearly 3 million undocumented immigrants, Cruz, Walker, and Rubio expressed sympathy for immigration before the 2016 election season. Cruz argued for doubling the cap on the number of immigrants America could admit every year; Walker supported a path to citizenship for undocumented immigrants; and Rubio helped write a 2013 Senate bill to create a path to citizenship.

Then, in 2015, Donald Trump—who, as a political neophyte, was largely unconstrained by traditional Republican views on immigration—jumped to the top of the polls in the Republican presidential race by denigrating Mexican immigrants and demanding a wall to keep undocumented immigrants out. Finding themselves on the wrong side of a tectonic shift in the GOP, his Gen X competitors jettisoned their earlier views. Asked in a 2015 debate why he no longer supported a path to citizenship for undocumented immigrants—a position, the moderator noted, that he had held “from 2002 until as recently as 2013”—Walker responded that he had “listened to the American people.” Rubio said that although he had helped draft the 2013 Senate bill that provided a path to citizenship, he hadn’t expected it to become law. Cruz claimed that an amendment he’d supported to dramatically increase the number of H-1B visas for foreign workers had been a ploy to sabotage the passage of any immigration bill at all.

The insincerity was obvious, and it didn’t work. In many primaries and caucuses, according to data published by FiveThirtyEight, Trump won the lion’s share of voters who called immigration their top concern. During his presidency, Rubio and Cruz have largely supported his immigration agenda in the Senate. That’s unfortunate. Comprehensive research suggests that while immigration imposes some fiscal costs, and disadvantages some Americans, it benefits the American economy as a whole. But these Gen X Republicans who once promoted that view have mostly gone silent.

Gen X Democrats have suffered a similar crisis of confidence. Consider Beto O’Rourke’s and Julián Castro’s shifting stances on trade. By the time each ran for city council in their Texas hometowns of El Paso and San Antonio in the 2000s, they had witnessed the effects of the North American Free Trade Agreement, which Clinton had signed into law in 1993. Initially, El Paso saw low-wage manufacturing jobs go south of the border, but over time, as Texas and Mexico grew more economically intertwined, fortunes rebounded. A 2016 study by the Federal Reserve Bank of Dallas found that since NAFTA had gone into effect, average income levels in El Paso and other Texas border cities had come closer to those in the nation as a whole. And according to the Bureau of Labor Statistics, the unemployment rate in San Antonio, which averaged more than 6 percent in the three years prior to NAFTA taking effect (the Bureau’s data starts in 1990), has averaged about 5 percent in the 25 years since.

Given the data, it’s not surprising that both O’Rourke and Castro hailed free trade before running for president. “Since the signing of NAFTA,” Castro declared in 2012, “San Antonio has blossomed into a major center of trade.” O’Rourke in 2015 voted to give Obama the authority to negotiate the Trans-Pacific Partnership, which, he said, offered the “chance for El Paso to capitalize on its growing status as a leading trade community.”

But as the Democratic Party has moved left, O’Rourke’s and Castro’s support for free trade has left them ideologically marooned. Castro now calls for renegotiating NAFTA, and has said he sympathizes with people who feel that many trade deals were “entered into with the concern of the big corporations first instead of the American worker.” O’Rourke wants to renegotiate it too, though not markedly, despite most studies showing that NAFTA has had a modestly positive overall impact on the American economy.

Kamala Harris’s retreat has been on truancy. In 2006, as San Francisco’s district attorney, she launched an initiative to reduce the number of students who chronically missed school without a valid excuse, a problem that, in the words of one 2005 study, had “reached epidemic proportions in urban academic settings.” The initiative was classically Clintonian, an effort to pair the two principles in which he grounded many of his policies: opportunity and responsibility. To help parents keep their kids in school, Harris created a hotline through which they could get referrals to services. Her office advertised the hotline on city buses that passed through neighborhoods where truancy rates were high. But she also sent a letter to parents warning them that truancy was against the law. Before prosecution, parents of truant children went through a lengthy, noncriminal process with school officials. But when that didn’t work, Harris’s office could bring them to court.

At the time, Harris’s tough-on-truancy policy fit the Democratic mood. Thirteen years later, it’s become a political liability. Numerous left-leaning commentators have slammed it as part of the criminalization of poverty that in recent decades has incarcerated vast numbers of young men of color. Progressives are right that the tough-on-crime policies of the Clinton era had devastating effects, and that Harris wrongly defended some of them. But her anti-truancy initiative—which she launched after studying data on the correlation between truancy during childhood and crime later on—was designed to keep people out of jail. And the effort appears to have kept kids in school: Between the 2007–08 and 2010–11 school years, the percentage of students in San Francisco public schools deemed chronically truant fell from 4 to 2.5 percent.

Progressive critics might argue that Harris could have achieved those results without threatening parents with fines or jail. But she didn’t lock up any parents of truants; very few even paid a fine. In most instances, judges dismissed cases on the condition that the parents took actions to get their kid to school. Why did it take a court summons to get some families the help they needed? It’s called the “black-robe effect.” For some people, a judge’s demand carries more weight than a school administrator’s plea, even when they’re urging the same thing. In the hardest cases, giving people an opportunity to get help isn’t enough—demanding that they exercise responsibility is necessary too.

Nonetheless, Harris has backpedaled. Although she declared in her 2009 book, Smart on Crime, that “fighting truancy might very well be the single most important thing we can do to impact the future of crime,” the issue is absent from the criminal-justice section of her campaign website. This spring, she said she regrets the way other California prosecutors implemented a 2011 statewide anti-truancy law that she’d pushed. In the current ideological climate, Democrats won’t even defend Clintonian policies that they know have worked.

Something similar has happened to Cory Booker on education. Booker, like Bill Clinton, once advocated for charter schools, which operate without many of the regulations that govern traditional public schools. After becoming mayor of Newark, New Jersey, Booker, according to The New Yorker, set out to make the city “the charter school capital of the nation.” Aided by an infusion of money from Facebook CEO Mark Zuckerberg and others, he made progress toward achieving that goal. From the 2009–10 to 2017–18 school years, the share of Newark students attending charter schools rose from 12 to 33 percent.

The data have been impressive. While achievement growth in math ended up flat, English gains in Newark schools have significantly improved since Booker launched his reforms, according to a study by the Center for Education Policy Research at Harvard. (Although funded by what is now the Chan Zuckerberg Initiative, the study—conducted by researchers at Harvard and Dartmouth—was peer-reviewed.) The study found that the movement of students from traditional public schools to higher-quality charters helped drive this progress. According to data from the Newark Board of Education, graduation rates have improved too. That finding is consistent with a 2015 study by the Center for Research on Education Outcomes at Stanford showing that students in urban charter schools perform substantially better than students in other urban public schools.

Nonetheless, as Bernie Sanders’s socialist message has gained influence, the mood inside the Democratic Party has turned against charter schools. Sanders has proposed a halt to government funding of new charter schools. Even a relative moderate, Pete Buttigieg, has called for slowing their expansion, according to NBC News. And Booker has dramatically muted his support for them; the education section of his campaign website makes no mention of charter schools. When Los Angeles teachers went on strike earlier this year, in part to protest the expansion of charter schools, Booker publicly supported them (though he didn’t link his support with their views on charter schools).

It is laudable when politicians admit they were wrong to champion policies that have failed. And many of the policies that enjoyed widespread support around the time Gen X politicians were first seeking office—from the Iraq War to mass incarcerationhave failed. Those failures laid the foundation for the ideological revolts that have transformed both parties since 2016, and those transformations were overdue. It’s a good thing that Donald Trump is more reluctant to attack Iran than George W. Bush was to attack Iraq. It’s a good thing that Democrats are now contemplating massive infrastructure investments to stave off climate change.

But there’s a fundamental difference between admitting you were wrong when the evidence has proved you wrong and pretending you were wrong when the evidence has proved you right, just because the political tides have shifted. It’s the difference between humility and cowardice.

By defending policies that have worked but are now ideologically out of favor, Gen X politicians could combat presentism, the recurring tendency—especially among progressives—to condescendingly dismiss the ideas of the past.

Young activists disdainful of the Clinton and Obama presidencies are remaking the Democratic Party. But new generations tend to overcompensate for the failures of their predecessors. In the 1960s, John F. Kennedy and Lyndon B. Johnson were so eager to distinguish themselves from the isolationists of the 1930s that they forgot that an earlier generation’s skepticism of war—born from the disillusionment of World War I—had lessons to teach despite the necessity of World War II. Heeding those lessons might have kept America from losing 58,000 soldiers in Vietnam.

After the economic woes of the Jimmy Carter years, Clinton-era New Democrats were so determined to prove that the party was not antibusiness that they deregulated Wall Street in ways that contributed to the 2008 financial crash. In the 1990s, many New Democrats also dismissed labor unions because of their belief in the free market. Today the pendulum has swung again, and Democrats eager for labor’s embrace are joining with teachers’ unions to oppose a charter-school movement that enjoys overwhelming support from African American and Latino Democrats.

As the in-between generation—old enough to have witnessed the Clinton era as adults but young enough to learn from its failures—Gen X Democrats could warn against the hubris of the present, as Ted Kennedy warned against Clinton’s endorsement of welfare reform in the 1990s and older foreign-policy thinkers like Reinhold Niebuhr and Walter Lippmann warned against Johnson’s escalations in Vietnam.

What matters most isn’t whether Gen X produces a president. It’s whether it helps America’s next president—whatever his or her generation—learn from the past rather than sneer at it.