Bernie Sanders was supposed to lose. Even he thought so.

In 1980, Sanders’ political career was already over. He’d retired after losing badly in four Vermont elections for U.S. senate and governor—plus a third-place finish for class president in high school. By his fourth election, Sanders got six percent of the vote, his best finish yet.

Today, Sen. Sanders (I-Vt.), who kicked off his presidential campaign in Vermont on Tuesday, is the most successful independent American politician in a century. Over a 40-year career, he’s faced a series of battles with the odds stacked against him. He faces what might be his toughest challenge today: beating Hillary Clinton in the 2016 Democratic primaries.

“Starting with the low-income and working-class wards, I knocked on as many doors as possible.”

Sanders is no stranger to surprise wins, however, even when the prevailing political winds seem to be blowing in the opposite direction.

In 1981, Sanders faced off in an extraordinary election against a local Democratic titan who was looking to win yet another race to add on to a decade of political dominance. Nearly everyone wrote Sanders off at the start, though few were enthusiastic about the odds-on favorite candidate.

Sanders won that historic race and changed the face of Vermont politics. With Clinton riding high as the presumptive nominee, Sanders’ supporters are wondering if he has another history-making moment in his arsenal.

Entering the 1980s, American liberals were on the retreat across the country. Ronald Reagan swept Republicans into power, including a solid 6-point win in Vermont. Democrats hadn’t taken the state in almost 20 years.

Sanders, then 39 years old, had run all of his previous campaigns knowing he would probably lose. It took a visit from a friend, Richard Sugarman, to convince Sanders that he had a chance to win his first major political victory.

“Richard, why should I run for office when I’m happily retired from politics?” Sanders recounts asking in his 1998 book, Outsider in the House. “How could I possibly win against an entrenched political machine? And what the hell would I do if, by some miracle, I actually won?”

The 6-percent vote that Sanders received in the 1976 gubernatorial election inspired little hope in him. Whereas previous elections were “educational” for Sanders and the electorate who heard him talk, the Brooklyn-born Jew felt little hope for a win.

Sugarman saw things differently.

In Burlington, Vermont’s largest and most liberal city, Sanders won twice as many votes, 12 percent total, during the 1976 race for governor. In the city’s poorest neighborhoods, he won 16 percent.

Sugarman, now a professor at the University of Vermont, argued that concentrating Sanders’ entire effort into the upcoming Burlington mayor’s race could end in victory.

It wouldn’t be easy.

Burlington, once the heart of a perennially Republican state, was becoming increasingly liberal, but it was already owned by centrist Democrats—a club Sanders was emphatically not a part of. Gordon Paquette, a five-term incumbent, came from a working-class neighborhood in the city, put together a strong bipartisan political coalition, and ran the city for a decade.

But Paquette’s years of running unopposed hit turbulence in 1981. Burlington’s economy grew under Paquette, but the city’s poor felt left out in the cold. Housing prices shot up, city services didn’t keep up with revenue growth, while controversial and costly urban-development plans catalyzed the opposition.

Paquette’s plan to increase property taxes by 10 percent inspired particular enmity from Sanders, who to this day views property taxes as regressive—it should be the rich who pay more, he’s argued for decades.

Despite Burlington being a relatively small city, critics regularly compared Paquette’s mayoral administration to big-city corruption seen in Chicago and New York.

While Republican Party and business leaders backed Paquette, Sanders banked on a expansive and contrasting coalition of the city’s poor, the emerging local counterculture, college professors, environmentalists, city cops, and even “conservative homeowners worried about rising property taxes,” Sanders explained in Outsider in the House.

“Starting with the low-income and working-class wards, I knocked on as many doors as possible,” he wrote. On those front porches, he pitched his candidacy and listened to the resident’s concerns.

That kind of energy spent on individual voters, especially in demographics that don’t usually vote much, can seem strategically suicidal. However, in a small city like Burlington—population 37,000, at the time—political change was in the winds. Vermont was shifting from a Republican stronghold to a liberal bastion. Burlington, never before a left-leaning town, stood on the precipice of political change.

In what would be an unfathomably close race, it quickly became obvious to Sanders that every single voter counted. Paquette, a decade into office, took considerably longer to realize there was any threat to his job, according to journalists covering the race for Vanguard Press, a local paper active throughout the 1980s.

Burlington’s citizens had a lot to say to Bernie. The housing authority ineffective and deaf to their concerns, Sanders heard, and poor neighborhood’s infrastructure was in disrepair.

“The campaign itself functioned as a crash course in Burlington’s problems and politics,” Sanders wrote. “In truth, I knew very little about Burlington city government. I had attended two Board of Aldermen meetings in my life—and had fallen asleep in one of them. They were boring.”

Most impactful, Sanders said looking back, was his promise to negotiate with local unions in good faith—a move that won him the crucial support of the local police union.

“The campaign itself functioned as a crash course in Burlington’s problems and politics.”

”I’ll be straight with you,” a 17-year Burlington police officer and self-described conservative told the Washington Post in the 1989. “At first, we were wary of Bernie Sanders. The socialism stuff. We didn’t know what to expect.”

Winning the support of cops was one of the key moves that won Sanders the Mayor’s office.

“They did so because I promised to listen to the concerns of cops on the beat and open serious labor negotiations with their union,” Sanders remembered.

A decade later, the union supported him still.

“But after eight years with him, I can tell you that he’s played fair,” the officer said. “The police respect him.”

Sanders, both during his campaigns and tenure in office, was called abrasive by his opponents in both government and business. That reputation has endured long past his time as mayor, even among allies.

“Bernie alienates his natural allies,” Former Rep. Barney Frank (D-Mass.) said in the 1990s. “His holier-than-thou attitude—saying in a very loud voice he is smarter than everyone else and purer than everyone else—really undercuts his effectiveness.”

Frank, who would be one of Sanders’ most liberal colleagues in the U.S. House of Representatives, eventually came to work well with Sanders.

In truth, “abrasive” is far from the worst thing an opponent has ever called Sanders. During his 1970s campaigns, words like “fascist” and “dictator” flew his way.

In his previous four defeats, Sanders had run as a member of the Liberty Union party. At the end of the 70s, he became an official independent—a self-described Democratic Socialist—free from the eye-rolls and sighs of resignation that accompany almost any third party in the United States. He drafted former Liberty Union organizers to help him run, a move that helped him among the lower-income portions of the city.

Higher-income residents saw something to like in Sanders as well. When he opposed private waterfront development that would have put high rise condos on the city’s scenic lakefront, Sanders received support from residents across the economic spectrum because the plan would disrupt the city’s natural beauty.

Furthermore, the plan would have cost $50 million—money spent at a time when bridges were falling apart. During debates, Sanders pointedly connected Paquette with unpopular developers. “I will totally oppose any more urban development projects that benefit the real estate developers and their allies at the expense of the ordinary citizen and taxpayer,” Sanders said at the beginning of his campaign.

Sanders’ two iconic campaign slogans came into being around this time. Artist Frank Hewitt protested against the waterfront condos with a poster that said “Burlington is not for sale.” Sanders’ campaign itself came up with the other slogan: “It’s time for a change. Real change.”

The “Democratic machine”—in reality a bipartisan creation—that controlled Burlington faced a strong challenge.

A significant number of Burlington business owners opposed Sanders in 1981—and continued to oppose him for the next decade. Although Sanders attacked higher property taxes for residents, he raised commercial property taxes as part of his policy to reform the Burlington tax structure so “those individuals and institutions who own valuable property … assume their fair share of the tax burden,” Sanders said.

Paquette, meanwhile, didn’t even bother to respond to Sanders’ nascent candidacy and criticism for months. He assumed he’d win once again, predicting a 70-percent victory, and he didn’t think it worth it to fight back in any meaningful way. It was only in the last weeks leading up to the polls that Paquette finally deigned to enter the fray.

Criticized as corrupt and complacent, Paquette assumed a fighting stance, arguing that he’d beaten Sanders to many of his progressive ideas.

“Five or six years ago, I said there comes a time when we will not be able to run the cities and towns on property taxes,” Paquette said two weeks before the 1981 vote. “Sanders is not new or innovative on the issue. He’s saying what I’ve said in the last few years.”

Paquette sold short Sanders’ vocal desire for radical change. Sanders call to reform property taxes was only part of the new progressive tax structure he aimed for, one that also included higher taxes on wealthy individuals and businesses.

A debate held in a local Burlington church just days before the poll was described, by Sanders’ supporters, as a hot-tempered affair that ended in a Sanders victory.

“When Sanders and Paquette debated at the local Unitarian Church, most of the audience was out for blood,” journalist Greg Guma wrote for the Vanguard Press in 1981. “And Sanders egged them on by linking the mayor with developer Antonio Pomerleau, who wants to build a condo/commercial-haven on the waterfront.”

“I’m not with the big money men” Paquette said angrily. “He’s trying to put me with them.”

If Sanders won, Paquette warned, Burlington would begin to look a lot like Brooklyn. In 1981, that was a scary proposition, as New York City reeled from decline. The attack didn’t work.

“The mayor looked honestly surprised when people hissed at him,” Guma wrote.

The response to Sanders’ performance was, on the other hand, “warm, virtually electric,” Guma wrote. “If the game had been football, the audience might have carried the challenger out on their shoulders.”

Endorsements from police unions, local liberal politicians, local family groups, and more infused Sanders’ campaign with optimism.

When the vote came in, it was close and lasted late into the night—which, for Burlington, is about 9pm. Until as late as 8pm, city tallies showed Paquette winning by a slim margin. It turned out to be the Republican strongholds of the city that pushed Sanders’ vote count over Paquette.

Sanders was declared the winner by 22 votes (out of 8,660), a number that allowed Paquette’s lawyers to file for a recount. When all the votes were counted once more, the margin dropped all the way to 10.

Against the odds and by the slimmest of margins, Sanders won. On that cold March day, even after it became clear that Sanders’ challenge was real, the shock reverberated around the city.

“The defeat of Gordon Paquette was so unexpected, however, that when I began to spread the news some people thought for sure I was joking,” Guma explained.

Paquette, seeing the end of his 23-year political career, predicted Burlington would “go down the tubes” with Sanders at the helm. On the contrary, the city experienced economic growth under the Sanders administration. His performance propelled him to office in the U.S. House of Representatives in 1990 and then, in 2006, the U.S. Senate.

After Sanders’ win, a defeated Democratic city politician said “the world is changing.”

The Democratic lieutenant governor at the time called Sanders after his victory and implored him: “Don’t do anything rash.”

The national shocked reaction to Sanders’ 1981 victory wasn’t the only surprise of his career, but it was the genesis of what has become a lifetime of political victories.

“His bumper stickers just say, ‘Bernie,’” Senator Patrick Leahy (D-Vt.) told the New York Times in 2007. “You have to reach a certain exalted status in politics to be referred to only by your first name.”

Before he ran for mayor in 1981, the smart money said Sanders would lose. After he won, many people assumed he’d be gone in two years. The Burlington City Council was famously uncooperative with him—they fired his secretary on his first day in office and rejected all his administration appointees—banking on his quick political evaporation.

“This wasn’t a fluke,” Sanders said on the night he won the election. “The people wanted a change, voted for a change. I intend to bring about change.”

“The people wanted a change, voted for a change. I intend to bring about change.”

Today, many—most notably, those in the influential mainstream media—dismiss Sanders’ race against Clinton as futile. Sanders has more support than much of the Republican field, but his presidential announcement was relegated to page A21 of the New York Times, while almost every other campaign received front-page coverage.

In primary states, Sanders is polling above 15 percent in primary polls in key states like New Hampshire. His name recognition is 58 percent, according to Public Policy Polling, second only to Clinton, a former first lady, New York senator, and secretary of state who’s sat atop the American political elite for more than two decades.

There’s no mistaking it: Clinton has a commanding lead. She’s sitting around 60 percent in all the primary polling and seems poised to win the Democratic nomination next year.

Sanders, however, has made a career of unexpected victories. The 1981 mayoral win was just the first. Two years later, he squeaked in again and began a decade-long tenure. In 1994, he withstood a historic tsunami of Republican success to remain the only socialist to hold national office. In 2006, he became the only socialist in the U.S. Senate. Today, he’s the longest-serving independent in American history.

A quick 34 years after that first big win, Sanders remains—as does the hope for surprises up his sleeve.

Illustration by Max Fleishman