For a generation struggling with student debt and increasingly passionate about social justice and the climate, Bernie Sanders's platform offered an appealing palette of promises - free university tuition, free healthcare, legal marijuana and a Green New Deal - intended to fire them up and bring about a genuine revolution.

Somewhere along the way, though, the revolution sputtered. When it came time to actually vote for their candidate, the youth Sanders was counting on did not come out in the numbers he was expecting. And the candidate himself was among the first to admit it.

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"Have we been as successful as I would hope in bringing young people in? The answer is no," Sanders said last week in a news conference from his campaign headquarters in Burlington, Vermont.

"I think that will change in the general election, but I will be honest with you," Sanders said. "We have not done as well with bringing young people into the process, it is not easy," he added.

Joe Biden's near sweep of Tuesday's primary elections in six states, including Michigan, was illustrative of the problem that has plagued Sanders throughout the 2020 campaign. Exit polls indicate that turnout among voters aged 18 to 44 actually declined since 2016, when a surprise win in Michigan gave the Sanders campaign new life and young enthusiasts accounted for 45 percent of the vote, and 2020, when young voters accounted for 38 percent.

It was the same story in earlier states.

In California, an early bright spot that Sanders won handily, voters under 30 years old made up only 11 percent of the electorate. Of the 14 states that participated in the Super Tuesday contest on March 3, participation of voters younger than 30 did not exceed 20 percent in any state. Voters between the ages of 45 and 64 consistently made up the bulk of voters.

Bernie Sanders speaking during a campaign rally at the University of Michigan in Ann Arbor, Michigan [Paul Sancya/AP Photo]

"There's a massive generational divide," said John Della Volpe, director of polling at Harvard University's Kennedy Institute of Politics.

In 2020, Della Volpe adds, young voters are not showing up at the rate they did in 2016. In Texas, for instance, 15 percent of voters were aged between 17 and 29 this election, compared with 20 percent in 2016.

"The youth vote relative to previous elections has been disappointing," Della Volpe told Al Jazeera. "There is plenty of evidence to suggest that Sanders did not optimise the turnout of his supporters," he added.

Under the campaign slogan "Not me, us," Sanders, 78, a self-described Democratic socialist railed against the political establishment, large corporations and billionaires and promised to tackle institutional racism and injustice in the country.

The rhetoric won him the endorsements of progressive firebrands such as Congresswomen Alexandria Ocasio-Cortez and Ilhan Omar, two rising stars with substantial support among youth. Ocasio-Cortez called Sander's struggle a "generational battle" that requires all hands on deck.

"It is going to be now, and in November, I believe the turnout of young people that will have a huge determination in our future as a country," Ocasio-Cortez said during an appearance on Late Night with Seth Meyers.

Some political analysts say Sanders, the oldest candidate running, who lost the Democratic nomination to Hillary Clinton back in 2016, is an unlikely figure to galvanize young support across the country and take on President Donald Trump in November.

"This whole notion that Bernie is a bridge to young people, was always a bit overblown," said Simon Rosenberg, a Democratic strategist and President of New Democratic Network, a think-tank based in Washington, DC.

"And the last couple of weeks have been proof of this," Rosenberg told Al Jazeera.

US Representative Alexandria Ocasio-Cortez with Bernie Sanders on stage during a rally at the University of Michigan in Ann Arbor, Michigan, US [Lucas Jackson/Reuters]

Max Pereboom, a 24-year-old Sanders supporter who has hosted several fundraising events in his home in Washington, DC, said that many young people, despite having a major stake in the country's future, have a hard time envisioning real change - especially of the sort Sanders champions.

"Most young people have never seen a political shift, never seen a real change," he said. "It's disappointing."

Other experts say convincing young people like Pereboom and his friends to head to the polls is a global challenge, and not limited to the US.

"Across the world, younger people are less likely to vote," D Sunshine Hillygus, author of Making Young Voters, a book that examines that challenge. Hilligus believes the commonly held perception that young people lack political engagement is false.

"The reason that young people have a low turnout is not because they are unmotivated or apathetic, they actually show high intent," Hilligus told Al Jazeera.

Bernie Sanders supporters cheering during a campaign rally in Phoenix, Arizona [Ross D. Franklin/AP Photo]

But for first-time voters, she says, the process of voter registration is often complicated and difficult, with strict deadlines, different rules in different states and confusion for students who live outside of their home state.

"Informational and institutional hurdles create a gap between intention and actual voting," she says.

If he decides to remain in the race, the road ahead will be a challenging one for Sanders. Primaries are scheduled for March 17 in Illinois, Ohio, Arizona, and Florida, and older voters make up the lion's share of the electorate in Arizona and Florida.

"We're doing a better job at it than most, but we need to do a lot better," said Amer Zahr, a comedian and a surrogate to the Sanders campaign.

"That's a challenge for our campaign, and that's a challenge to every campaign in the history of politics, to get younger people out to vote," Zahr told Al Jazeera.