Joe Biden’s decision to forego a run for the White House in 2016 was, for many Democrats, his moment of highest statesmanship. Biden’s difficult decision, racked as he was with grief at the loss of his son Beau, elevated the vice president to heroic status not only within the Democratic Party, but with voters across America. There was something superhuman in the Biden who set aside his well-known ambitions to nurse a private and consuming grief.

As the 2016 campaign grew ever nastier, the retired Biden came to embody Democratic dreams about what might have been. His absence allowed voters to project their own deeply held values onto an imagined Biden campaign in much the same way Democrats in 1968 allowed themselves to imagine what America might have achieved under President Robert F. Kennedy.

I dreamed, too. I imagined how much more engaged voters would’ve been with an effervescent, optimistic Joe Biden running against the darkness of Trumpism. I imagined his working-class image lighting up labor union rallies in Michigan and Pennsylvania. Biden was still “Uncle Joe.” He still reminded us of the possibility of the Obama years.

But that didn’t happen. Instead, we entered a dark new era in American politics, one defined by Muslim bans and immigrant children dying in cages on the Texas border. The outrages of Trumpism brought an entirely new generation into the Democratic fold. Millennials took to heart President Obama’s bold challenge that “we are the change we’ve been waiting for.”

After three years of Donald Trump, millennials are tired of waiting.

Donald Trump’s unlikely 2016 victory fundamentally reshaped the fault lines within the Democratic Party. A recent analysis by Politico reveals a party where traditional ideological divides have given way to deeper conversations about race, identity and the quality of life in America.

The gun-violence epidemic and the corrosive impact of mass incarceration on communities of color—issues now considered central to the Democratic identity—are in the national conversation because a new wave of young activists put them there. Their success redefined how young activists related to the Democratic Party. It also reshaped their relationship to candidates like Biden, who now represents an incrementalist approach to tackling pressing national crises rejected by ambitious millennial activists.

The students of Marjory Stoneman Douglas High School organized a national campaign for gun safety reform, prodding the Democratic Party to adopt a more focused and uncompromising view of the threat posed by our national addiction to firearms. In some cases, like the nationwide youth movement against mass incarceration and the War on Drugs, millennials fought and won electoral victories even when it meant ousting incumbent Democratic prosecutors.

Unlike the current Democratic establishment, mission-driven millennials refuse to put party orthodoxy ahead of the issues that brought them into political activism. Biden has struggled mightily to internalize this aspect of the millennial moral universe. Biden has often tried to silence Medicare for All advocates by claiming their advocacy is tantamount to slandering the legacy of Barack Obama’s Affordable Care Act.

Biden’s claim doesn’t just question the loyalty of Medicare for All advocates, it fails to understand why most millennials feel Obama squandered an opportunity to pass a fully progressive health law by compromising with the Republican minority. The ACA Biden holds up as a crowning achievement looks, to many younger voters, like a premature progressive surrender.

Biden gravely miscalculates the political cover his service under Barack Obama provides. When it comes to Obamacare, Biden positions himself as almost co-equal in sharing Obama’s glory. But when it comes to more difficult issues like Obama’s record number of immigrant deportations, Biden claims political impotence. But the more Biden twists himself into a political pretzel, the more millennials lose faith in his vaunted frankness.

Millennials have rallied around candidates who are unsparing in addressing their faults as well as their strengths. South Bend Mayor Pete Buttigieg’s honest appraisal of his challenges in attracting African-American voters provides an object lesson, as does Bernie Sanders’ apology to female staffers who alleged mistreatment during his 2016 campaign. In today’s Democratic Party, leadership means sometimes having to say you’re sorry.

Millennials aren’t looking for perfection, but they do expect self-awareness—and that may be Biden’s biggest stumbling block. On multiple occasions, the former vice president has struggled to understand just how much the emergence of millennials has changed the Democratic Party’s DNA.

In 2008, few mainstream voices analyzed Biden’s role in the disastrous 1994 Crime Bill. At the time, the Democratic Party was still recovering from its misguided “tough on crime” phase. A decade later, an expansive criminal justice reform movement empowered by millennial leaders made Biden’s Crime Bill support into a central criticism. This time, major media outlets like Vox and MSNBC covered the 1994 bill’s failings in depth. Even former President Bill Clinton formally apologized for his role in its passage.

For weeks, Biden swung between strident defense of his legacy and near-apologies. On June 6, he defended his leadership on the Crime Bill. By July, Biden reversed course with new criminal justice proposals that reversed large sections of the 1994 bill.

It isn’t just the Crime Bill, either. Biden has shown a shocking willingness to paint millennial policy concerns as petulant whining undeserving of serious consideration. “The younger generation now tells me how tough things are. Give me a break,” Biden said in a Los Angeles Times interview. “No, no I have no empathy for it—give me a break.”

There’s little evidence Biden has learned his lesson. In late November, Biden came out against legalizing marijuana in a speech that used the debunked trope that cannabis is a “gateway drug.” Biden’s factually incorrect return to the scaremongering language of the 1990s rightfully inflamed the Democratic base. Not only was Biden wrong on the data, his view of marijuana is one that resulted in the mass incarceration of millions of black and brown Americans.

Less than two weeks later, Biden sheepishly walked back his anti-marijuana stance, staking out a polar-opposite position in favor of legalization. Displays like that make Democratic voters nervous. What other deeply held values will Biden toss overboard at the first sign of political turbulence?

Dismissing millennial issues is a losing strategy, as Biden’s main challengers Elizabeth Warren, Pete Buttigieg and Bernie Sanders instinctively understand. The numbers support their caution: the 2018 midterm election marked the first time millennials and Gen Xers outvoted Baby Boomers, according to Pew Research Center. Biden could safely ignore young voters in 2008. It’s a different story in 2019.

Faced with a dismissive Democratic establishment, millennials set about building their own bench. They made national celebrities out of Rep. Alexandria Ocasio-Cortez and her squad of progressive, DNC-bucking legislators. They propelled Buttigieg, Warren, and Sanders to the top of a wide-open Democratic primary race. And they increasingly see little reason to compromise with Joe Biden when other viable candidates wholeheartedly embrace their core issues.

The 2020 election offers millennials an unprecedented opportunity to show their strength and alter the course of the Democratic Party. Joe Biden antagonizes them at his own risk.