In the dazzling Spring sun on Wednesday morning, shoppers at the open-air Aligre market in eastern Paris were eyeing which asparagus, mushrooms and apples looked best to buy. But amid the talk of food, there was a much more serious discussion underway, too: Whether to vote for a far-left presidential candidate who espouses shorter working weeks and higher taxes in the first round of elections on April 23.

Jean-Luc Mélenchon, founder of a left-wing party called “France Unbowed” and backed by the Communist Party, has soared in the polls over the past month, as France’s most unpredictable presidential race in decades draws to an end.

With only 10 days to go until the first-round of voting, he is drawing close to even with the race’s frontrunners — centrist independent Emmanuel Macron, scandal-tainted conservative François Fillon and the far-right National Front’s Marine Le Pen. “The Mélenchon Moment,” reads Thursday’s front cover of the national newspaper Libération. He is attracting giant crowds across France, on a populist message of taxing the rich and protecting workers’ rights.

The message is finding a receptive audience. The Socialist Party’s near-collapse as a political contender under unpopular President François Hollande had many commentators in France pronouncing the death of the modern French left-wing. But there’s increasing evidence that, after years of double-digit unemployment and near-zero growth, many French voters appear eager to listen to far-left political ideas.

During the country’s first-ever presidential debate to include all 11 candidates running on April 4, the most memorable performance was by the New Anti-Capitalist Party’s Philippe Poutou. The 50-year-old works on the assembly line in a Ford Motors factory in Bordeaux, making gearboxes, and proposes nationalizing France’s huge energy companies and its banking sector.

In stark contrast to the other suited and booted candidates, Poutou wore a long-sleeved T-shirt to the debate, and refused to pose for the traditional “family photo” of all the candidates before the debate began. “I’m not part of that family,” he told TIME by phone on Wednesday. “We are not at all in the same world,” he says. “They are all totally disconnected from the population, totally privileged.”

He scoffed at the others on stage during the debate, reminding them that he was the only one “with a real job.” “Even Jean-Luc Mélenchon was in the Socialist Party for 30 years, and was a minister for a few years,” he told TIME. “Politics is corrupt, it favors rich people.” He says he his mailbox has been jammed since the debate with thousands of letters, from people urging him to fight on, and “some calling me a hero,” he says.

Poutou is forecast to win only a tiny fraction of votes, but some polls suggest Mélenchon could even make it to the run-off second round on May 7. Though it’s still an outside chance, that would represent a stunning comeback for the French far-left. Mixed with his firebrand style, Mélenchon’s argument that France’s richest one percent sucks up the vast bulk of France’s wealth has swept through the country with intense momentum.

“It is the same situation as it was in the U.S. with Bernie Sanders,” says Nicolas Bonnet Oulaldj, a Communist Party delegate to Paris’s city council, as he stood in the Aligre market, handing out election flyers to passersby, and urging them to vote for Mélenchon. “There is a return across the world to people questioning how politics is being influenced by money,” he says, explaining what he believes is Mélenchon’s appeal. “All the dynamic today, all the polls, shows Mélenchon as the only candidate who is rising.”

Mélenchon does have some things in common with Sanders; at 65, he is the oldest of all 11 candidates in the race has a long reputation for railing angrily against the cloistered political elite. His platform too includes scrapping free-trade agreements with the U.S. and Canada.

But in other ways he is far more radical than the Vermont senator. He would tax incomes above €400,000 at 100 percent, vastly increase public spending, and cut the workweek from 35 hours to just 32. He also wants to withdraw France from NATO and impose staunch pacifism.

On Wednesday night 12,000 people packed a hall in the northern city of Lille to hear Mélenchon pound his message for more than two hours, while hundreds more spilled out on to the streets. In his trademark open-neck shirt, Mélenchon told the crowds that Le Pen, Macron, and Fillon—were all a “catastrophe.” “If you elect these three you are going to spit blood,” he thundered. And last Sunday tens of thousands of people poured on to the seafront promenade of Marseille, where he whipped his supporters into cheers for dramatic change in France.

The speed of Mélenchon’s rise has been striking. A poll by Ifop Fudicial on Wednesday showed a 68 percent approval rating for him, compared with 22 percent just one month ago, while another poll by Elabe found that 24 percent of voters believed he was the “best to change France,” ahead of Macron, at 23 percent, and far ahead of Le Pen’s 16 percent. The candidate for the ruling Socialist Party, Benoît Hamon, has collapsed, trailing far behind at about nine percent.

“Mélenchon represents something important in French politics: Dégagisme,” Edouard Lecerf, Global Director of Political and Opinion Research for Kantar Public polling agency, told TIME on Wednesday. The word translates as “get-out’ism,” or voters’ desire to throw out traditional political leaders in favor of insurgents and populists.

Most predict that Macron and Le Pen would reach the second, decisive round on May 7, and that Macron would handily beat Le Pen, as millions vote against her anti-immigration views that many young liberals find repellent. But polls suggest about 40 percent of people have not yet decided who to vote for.

Oulaldj, the Mélenchon campaigner in the street market on Wednesday, says he will urge people to vote against Le Pen in the second round, no matter who her opponent is, saying it is “too important” to leave such a decision to chance.

But what if the run-off round is between Le Pen and Mélenchon? To business leaders and conservatives, the prospect of a Le Pen-Melenchon run-off vote is chilling. Pierre Gattaz, head of France’s powerful business federation, calls it a choice “between economic disaster and economic chaos.”

Indeed the prospect is also roiling markets. The euro fell against the dollar last week with news of Mélenchon’s rise, and the gap between French and German bonds widened. “French political risk is back!” ABN Amro said in a note to investors on Monday.

That risk factor underscores the unpredictability of this race. “If Macron or Marine Le Pen become a little bit weaker in a week or so, then we will have three, not four, at about 20 or 21 percent,” says Lecerf of the Kantar polling agency, adding that this election campaign is the most difficult to predict in his 30 years of polling. “That allows for every hypothesis possible.”

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