WATCH: Clinton Loses Every Demo In New Hampshire – Except 65-Plus

MANCHESTER, NH — (CNN) The Iowa caucuses were days away, and Hillary Clinton’s campaign had tapped “In the Attic” — a band of four 19- and 20-year-olds from Cedar Rapids — to warm up the audience before she, Bill and Chelsea took the stage.

Two days later, the band caucused for Bernie Sanders.

“We like Bernie, but we think Hillary is a solid candidate,” Grant Blades, the band’s 19-year-old frontman, told CNN in an interview in an effort to be diplomatic.

Then 20-year-old drummer Tanner Parks dropped it, saying, “OK, we are supporting Bernie.”

They aren’t alone in choosing Sanders. Tuesday night in New Hampshire, 83% of voters aged 18-29 chose Sanders, according to exit polls. And those voters were a full one-fifth of the electorate. Sanders also won 78% of first-time voters. The only age demographic Clinton won? People 65 and older.

Clinton acknowledged the gap in her concession speech.

“I know I have some work to do, particularly with young people,” she said. “But I will repeat again what I have said this week: Even if they are not supporting me now, I support them.”

The overwhelming support for Sanders — a disheveled 74-year-old who has spent two decades in Congress — among younger voters is perhaps the biggest challenge confronting Clinton’s campaign in the Democratic nominating contest. It also underscores the problem with what Clinton represents: In a year that voters are craving authenticity and a break from the political norm above all else, her nearly three decades in the political limelight is a liability.

“Hillary just seems like a normal Democrat, and Bernie seems a little revolutionary to me,” said Jonah Hunt, an 18-year-old high school senior in Rochester, New Hampshire.

For Clinton to win the Democratic nomination, or at least stave off a lengthy, damaging primary fight, she needs to win over those voters — and those she can’t win now, she’ll need on her side if she advances to the general election.

The advantage for Sanders extends beyond support at the polls. His supporters have built social media campaigns — Twitter Bombs — designed to inject Sanders’ campaign with thousands of new, small-dollar donations.

Clinton’s campaign aides have acknowledged they need to close the age gap with Sanders, but remain confident she will be able to win them over by speaking directly to issues that they care about, namely college affordability, social issues and women’s rights. Aides also feel targeted rollouts like the one she made on campus sexual assaults in Iowa earlier this year will help.

“Go out there and talk to young people. She’d be way better for them,” Bill Clinton told supporters Monday afternoon in Rochester.

Sanders had visited the same town just two days earlier, and had drawn local high schoolers to his rally at city hall.

Al Spader, a 37-year-old sixth grade science teacher, said he ran into several of his former students there.

“He’s very genuine, and he’s offering to help them out — and I think he’s empowering them,” Spader said. “They’re actually understanding that message.”

His description of Sanders — “genuine” — comes up constantly in interviews with young voters.

“Bernie is really in touch with the middle class. I know Hillary claims that she is, but I really don’t feel that. She’s been wealthy for so long,” said Gillian Under-Mochrie, 18. “It’s just refreshing to see a candidate who really gets it.”

Clinton’s campaign has turned to celebrities — namely Lena Dunham, Christina Aguilera and America Ferrera, among others — to court the generation Sanders has captivated.

And the campaign has also tailored their media strategy to young people. Clinton joined Snapchat and now snaps about Planned Parenthood and other issues important to millennials. (Sanders, too, has targeted young people on Snapchat, with different themed filters each day leading up to the Iowa caucuses, and he benefits from a hugely active base of support on Facebook.)

She has participated in interviews aimed at young people, too, like when she chatted with BuzzFeed’s “Another Round” podcast. And the campaign has engaged with Internet “influencers,” like working with Karen Civil and sitting down for an interview with Glozell Green.

Chelsea Clinton — someone the Clinton campaign sees as an asset with younger voters — has also started to hit the trail for her mother, campaigning in Iowa and New Hampshire and headlining fundraising events.

And to be sure, Clinton has young supporters, too — some of whom attended an event at Grand View University just before the Iowa caucuses.

They said what they’ve heard about Sanders from fellow students makes them worry he’d lose a general election.

“The fact that he’s a socialist — that’s probably the biggest reason I wouldn’t vote for him,” said Danni Finn, an 18-year-old elementary education student from Glenwood, Iowa.

The generational divide — particularly among women — is the subject of an increasingly bitter battle between campaign surrogates and supporters.

Clinton lost the vote among women Tuesday night, 44% to Sanders’ 55%, according to exit polls.

The disconnect: Older women who waged the wars against sexism don’t understand why the prospect of the first female president doesn’t excite their younger counterparts; younger women see presidential politics as open to their gender now, so electing a woman in this election — as opposed to any that follow — doesn’t seem pressing.

“There is a special place in hell for women who don’t help each other,” former Secretary of State Madeleine Albright said at a rally for Clinton in New Hampshire.

Then came a rebuttal from Emily Ratajkowski, a 24-year-old model who spoke at a Sanders concert and rally Monday night at the University of New Hampshire.

“I want my first female president to be more than a symbol,” she said.