The stakes are looking higher than expected in Tuesday’s Democratic primary in New York. With Bernie Sanders racking up victories in eight of the last nine contests — some by very large margins — former New York Senator Hillary Clinton needs a convincing win over Sanders, himself a Brooklyn native, to quash concerns her presidential campaign is slipping.

A February poll showed Sanders 21 points behind Clinton in New York, a state with a whopping 247 delegates at stake, but the latest polling narrows the gap to between 10 and 14 points. “They’re very worried about a Zephyr Teachout situation,” a Clinton supporter close to the campaign told Politico.

A what?

For those of us who have not always followed New York politics as closely as we have this week, a “Zephyr Teachout situation” does not refer to some sort of breezy teaching contest or an instructive meteorological protest. It refers to the progressive challenge to the state’s powerful sitting governor, Andrew Cuomo, mounted by a 42-year-old Fordham Law School professor named Zephyr Teachout in the Democratic gubernatorial primary in 2014.

Teachout’s message alone seemed to resonate, even without the cash to back it up.

Teachout, who did not respond to requests for comment, lost, but she surprised nearly everyone by securing 34 percent of the vote and winning more than two dozen counties. Cuomo outspent Teachout’s last-minute campaign about 40 to 1, but her efforts, despite little money, organization or name recognition, provide a ray of hope for Sanders supporters gunning for a Clinton upset on Tuesday. Can Bernie, with his small-donor coffers and army of volunteers, replicate Teachout’s relative success to an even greater extent on the same terrain?

A Vermont native and graduate of Yale University and Duke Law School who worked as a death-penalty lawyer in North Carolina, Teachout cut her teeth in politics on Vermont Governor Howard Dean’s 2004 presidential run, helping the innovative campaign mobilize its legion of Deaniacs online. Prior to throwing her hat in the gubernatorial ring, she was a law professor involved in Occupy Wall Street and interested in open government and combating political corruption.

The academic turned activist finally turned political candidate in June 2014, when, after not getting the liberal Working Families Party’s nomination for governor, she announced she would challenge Cuomo directly in that year’s Democratic primary, just three months away in September. “The core of my platform,” Teachout told USA Today in a statement reminiscent of Sanders, whom she has endorsed in the current presidential contest, “is to change the role of money in politics, support public education and break up monopoly power.”

Teachout may have been dedicated to taking the big money out of politics, but she still had to get some of it into her own campaign to stand a chance. And after Cuomo tried to get her kicked off the ballot, contributions started to flow in, giving her bare-bones campaign about $600,000, enough for some targeted online advertising and a tiny office in Midtown Manhattan for fewer than a dozen staff members.

On the trail, Teachout tapped into the antiestablishment sentiment among the state’s teachers, public employees and fracking opponents. She would ask voters point-blank what they were looking for in a governor and relied on public transportation and rides from volunteers to reach events across the state. Teachout, as The New York Times observed, “is zestily campaigning with a kind of cynicism-free optimism that makes her a sunny surprise.”

But the biggest surprise of all came on primary day, when Teachout pulled down more than a third of the vote and nearly shut out Cuomo in the Hudson Valley. Overall, it was a decisive victory for Cuomo, but in relative terms, it was one of the worst primary performances for an incumbent governor. And, according to an analysis by The Washington Post, Teachout, who is currently running for Congress in New York’s 19th district, spent just $1.57 per vote, compared to Cuomo’s $60.62. Teachout’s message had clearly resonated, even without the cash to back it up. Imagine how well she could have fared had she run a direct-mail campaign or a single television ad … or if she were named Bernie Sanders.

“As Zephyr Teachout demonstrated, there is a natural base for Senator Sanders’ kind of politics in New York,” says Jim Manley, a veteran Democratic strategist who supports Clinton. Sanders has heavily targeted the districts where Teachout won in 2014, but there is still a very firm ceiling Sanders will likely encounter, particularly statewide. “While Sanders, like Teachout, will tap into progressive activism,” says Manley, “I’m not so sure how much that is going to matter once you get out of New York City proper and start looking at the state as a whole.”

Even if Sanders doesn’t win New York, a closer than expected finish could mean a largely Pyrrhic victory for Clinton. For Sanders, by contrast, defying the odds could give his campaign something far different — call it a Zephyrric victory.