Step aside, Bernie Sanders, or maybe step it up: A new poll of young voters finds that Sen. Elizabeth Warren of Massachusetts is gaining quickly on the Vermont senator in the Democratic primary race, challenging Sanders among a voter demographic he dominated in 2016.

The survey of 18-29-year-olds by the Harvard Kennedy School's Institute of Politics found that while Sanders is still the favorite, with 28% support, Warren has surged to a close second, with 22%. That represents an enormous leap from the spring survey, which had Warren in fifth place, with just 4% support among young voters. In the current poll, former Vice President Joe Biden garners 16%. No other candidate in the crowded field has more than single-digit support.

Sanders' strong challenge to Hillary Clinton in the 2016 Democratic primary was largely due to his support among young voters. An analysis that year by the Center for Information & Research on Civic Learning and Engagement found that in the 21 states that held nominating contests by June 1, Sanders won more than 70% of the vote among people 18-29. In raw vote total, the self-described democratic socialist who made free college a central part of his campaign earned more votes among young people than both Clinton and then-GOP nominee Donald Trump combined.

But mirroring her rise among Democratic voters overall, Warren is quickly gaining steam among young voters, according to the IOP poll, the organization's 38th survey of the political preferences and social views of young Americans.

Some of the surge may have to do with Warren's personal biography – she calls herself a capitalist, while Sanders defines himself as a democratic socialist, says John Della Volpe, director of the poll. But Warren has also been able to market Sanders' 2016 message in a way that is drawing youth, he adds.

"At the end of the day, she's talking about what voters have been telling us – that we need to address the inequalities in American democracy and our economy, and that structural change and reform is what is required," Della Volpe says.

Businessman Andrew Yang comes in fourth, with 6%, followed by South Bend, Indiana, Mayor Pete Buttigieg with 4%, former Rep. Beto O'Rourke of Texas with 4%, and Sen. Kamala Harris of California with 3% support. O'Rourke withdrew from the race Friday.

Former Housing and Urban Development Secretary Julian Castro, Rep. Tulsi Gabbard of Hawaii, Sen. Cory Booker of New Jersey and billionaire activist Tom Steyer are each pulling 1% among young people. Other Democratic contenders in the poll received less than 1%, and 12% indicated that they were undecided.

Warren on the Trail View All 17 Images

Warren's jump in the polls is similar to the trend before the last presidential election, Della Volpe says. In the IOP's 2015 polling, Sanders went from single digits to leading the field by fall, as enthusiasm for the candidate grew.

The current polling "is good news and bad news for Sanders," Della Volpe says. "The good news is that his platform, which was considered far left in 2016, is still considered left but far more in the mainstream than just a few years ago. The bad news is that because he was so influential (with) his policies in 2016 and 2017, he has more competition" for progressive and young voters, Della Volpe adds.

Young voters are fired up to vote next year – and the vast majority won't be casting a ballot for the incumbent president, the poll shows. While two-thirds, or 67%, of young Republican primary voters say they will vote for Trump, 68% of general election voters 18-29 say they will never vote for Trump or are unlikely to do so. A little more than a fifth – 22% – of young GOP primary voters say they are undecided.

The numbers are in sync with a Washington Post/ABC poll published over the weekend , which showed 18-29-year-olds had the dimmest view of the president, with 22% of that age group saying they approved of Trump's job performance. That age group was also the most likely to say the president should be impacted and removed from office, with 58% sharing that view.