Kayla Shelley entered 2020 fired up and ready to fight. The 22-year-old progressive spent weekends knocking on doors for Sen. Bernie Sanders, a candidate the St. Cloud resident believed could deliver on a vision of economic and social justice — and beat President Donald Trump.

But just two months after Sanders dominated the first three nominating contests, former Vice President Joe Biden emerged as the Democratic Party's presumptive nominee. As Shelley looks ahead to November, "disappointed is an understatement."

"Don't expect us to jump up and down to vote for the lesser of two evils," Shelley said. "Ideally, no one wants to vote for what they feel is the less bad option."

Sanders endorsed Biden in a show of unity last week, urging his supporters to join him in helping the Democratic nominee beat Trump. But lingering disillusionment among die-hard Sanders supporters such as Shelley portends a potential challenge for Biden as he pivots to the general election: winning over young progressive voters, many of whom backed his rivals in the primary this year.

Young people traditionally vote at lower rates than older members of the electorate, even in Minnesota, a national leader in youth and overall turnout. But high participation levels from liberal-leaning young voters in the 2018 midterms, including in Minnesota, have been credited with tipping the scales for Democrats in some close races. A Star Tribune/MPR News Minnesota poll conducted in February found that 3 in 4 registered voters 34 and younger plan to vote this November.

"I absolutely think that young people are going to be deciders in 2020," said Abby Kiesa, who studies youth voting as director of impact at a Tufts University center known as CIRCLE. "Young people have had an impact on statewide races being competitive and a profound impact on candidates winning a state and holding a state."

Given the stakes, both sides are expected to heavily court young voters this fall, especially in Minnesota and other battleground states. The Trump campaign, which has been active on the ground here for months, has been in touch with the state College Republicans. A virtual day of action is planned for this week.

The Biden campaign, fresh off the primary fight, is also increasing its digital efforts as the coronavirus pandemic upends traditional outreach. A spokeswoman said the campaign "has been engaging directly with young people from virtual happy hours to individual conversations to make sure our next generation of voters and leaders are heard."

"Minnesota has a proud tradition of grass-roots, progressive activism that is fueled by young people who are passionate about the future of our country," Biden spokeswoman Julia Krieger said in a statement. "That's why in this virtual stage, our campaign has been building on its strong foundation of support across constituencies and issues — reaching out to supporters of previous presidential candidates and voters of all political stripes to unite and mobilize our party."

Some primary data suggest the former vice president could face an uphill battle to energize young Democratic voters in Minnesota and across the nation. Sanders outpolled the former vice president among voters 29 and under in the vast majority of caucus and primary contests, a CIRCLE analysis showed. Despite a landslide victory in Minnesota, Biden got support from just 17% of the state's voters under age 29, the analysis found. Sanders carried 65% of the youth vote.

"He made people feel heard and seen," said Emily Wellen, a veteran organizer and executive director of the Minnesota Youth Collective, a progressive political nonprofit. "Young people were partners in that campaign in a way they haven't been in other campaigns."

The CIRCLE analysis showed some bright spots for Biden: Turnout among young voters in the Democratic primaries was up in many states, compared with previous presidential cycles featuring a contested field on only one side. And Biden won youth voters by a wide margin in Mississippi, a state with a substantial black electorate.

Kiesa said the overall primary results show the campaign "has an opportunity here to really reach out to young people" by directly engaging young leaders on the ground and focusing on issues these voters care about.

Wellen agrees that issues drive young voters to the polls. She said many of the teens and 20-somethings involved in her organization are hungry for large, systemic change: "Going back to the way things were before Trump isn't a motivating enough reason to cast a ballot in November."

Sanders has pledged to push Biden's campaign to embrace some of the progressive policies he has championed. And Biden has already made some overtures aimed at Sanders' young base, including backing tuition-free public college for many and lowering the Medicare age to 60, seen as a nod to Medicare for All.

Minnesota College Democrats President Brayden Sorenson said many young Democrats see those moves, along with a recent endorsement from Sen. Elizabeth Warren, as a "step in the right direction."

Sorenson's group remained neutral in the primary, as did many campus chapters. Sorenson acknowledged that many young, enthusiastic Sanders supporters are still going through a "grieving process." But the Concordia College student is confident many will turn out for the Democratic nominee.

"While some young people may not be super excited about the Biden campaign, they're super excited about electing Democratic candidates, whether its president or school board or anything in between," he said.

Sean Duckworth, a 29-year-old Biden supporter from St. Paul, has also seen a shift to a "vote blue no matter who mind-set" among peers, including those who backed other candidates. "He really is the best chance we have to get some of these things we want, like dealing with health care and climate change and student debt," Duckworth said of Biden. "If you don't vote for him, you're not going to get any of that."

Not all young progressives share that view. "We're out of time for incremental change, and that's why we really can't endorse a candidate that doesn't embrace the full radical change we need," said Priya Dalal-Whelan, an organizer with Minnesota Youth Climate Strike.

Dalal-Whelan was a freshman in high school when Trump won the White House in 2016. "I really hoped I would graduate and be able to move into college and start November voting for someone I believe in," she said. "That's not happening."

Shelley, the Sanders volunteer from St. Cloud, feels similarly deflated. The 22-year-old can't imagine actively campaigning for Biden and plans to pour time and energy into state and local races instead. But the idea of not voting is also hard to stomach.

"I'll probably show up in November," Shelley said. " But I'm not going to feel good."