In June, Bernie Sanders called for former Brazilian president Lula da Silva to be released from prison.

Today, it is clearer than ever that Lula da Silva was imprisoned in a politicized prosecution that denied him a fair trial and due process. During his presidency, Lula oversaw huge reductions in poverty and remains Brazil’s most popular politician. I stand with political and social leaders across the globe who are calling on Brazil’s judiciary to release Lula and annul his conviction.

Four months and multiple Democratic debates later, none of the other candidates have followed his lead. That’s a travesty. Not only is Lula a political prisoner by any reasonable definition, but he’s a figure who should be celebrated by anyone who wants to defeat the global forces of right-wing populism.

In 2018, the former two-term Brazilian president, who had a commanding lead in every poll over the eventual winner Jair Bolsonaro, was removed from the race and sent to prison for “indeterminate acts.” He was accused of accepting upgrades on a modest seaside apartment, but no evidence that he owned it or even visited the property more than once or twice was ever produced.

Leaks published by the Intercept Brazil show that the prosecutors themselves were worried that they didn’t have a case even on this petty charge — and that they (and the presiding judge) were motivated by concern that Lula and his Workers Party (PT) would win the upcoming election. Despite these blockbuster revelations, Lula remains behind bars.

This is obviously a great injustice in itself. It also has much wider implications. Bolsanaro, who has said that his only objection to the military dictatorship that once ruled his country is that it didn’t kill enough leftists, is presiding over what amounts to an ecocide of the Amazon. In addition to violating the human rights of the Amazon’s indigenous inhabitants, this poses a grave threat to the earth’s biosphere.

All of the Democratic candidates claim to care about climate change. They all make noises about defending democracy. Yet when it comes to Brazil, where the two issues urgently come together, Bernie stands alone.

During the years in which Lula was president of Brazil, his policies lifted 40 million Brazilians out of poverty. He eliminated hunger, increased wages, and radically expanded credit and educational opportunities while expanding Brazil’s stature in the world. He combined big social-democratic ambitions with a pragmatic streak that allowed him to work with Brazilian and international power structures, pay off Brazil’s debt to the IMF, and for a time maintain friendly relations with everyone from George W. Bush to Hugo Chavez.

It’s instructive to contrast the path right-wing populists took to power in the United States, where Hilary Clinton lost a close election to Donald Trump, or the UK, where the electorate voted for Brexit even while the top leadership of all the major parties campaigned against it, to the rise of Bolsonaro in Brazil. To defeat the governing left party, the Brazilian right had to first impeach Lula’s successor Dilma Rousseff on grounds so dubious that even Michel Temer, who replaced the impeached Rousseff until new elections could be held (and who certainly seemed to welcome the process at the time), has recently described Rousseff’s impeachment as “a coup.”

Even after Rousseff was removed, Lula himself, now eligible to run for a new term, would by all indications have easily defeated Bolsonaro if he’d been allowed on the ballot. Anyone alarmed by Trump, Brexit, and the rise of right-wing populists around the world should ask themselves what Lula and the PT were saying and doing that center-left forces elsewhere in the world were not.

For one thing, they achieved concrete material gains for their social base. Where American Democrats made the thin argument that the recovery would have been even slower without Obama’s stimulus, there was no room for ambiguity with the tens of millions lifted out of desperate circumstances in Brazil. For another, Silva is one of the most skillful political communicators in the contemporary world.

He was born into extreme poverty. He didn’t learn to read until age ten. As a leader of Brazil’s labor movement, he helped bring down the country’s military dictatorship before being elected president himself. He described what happened next in his letter from prison to the conference of the UK Labour Party: “Never before had a factory worker reached the highest office in Brazil. For that reason, I needed to prove that the working class is capable of governing, and that governing for all, but with special care for the neediest, will always be the surest path to building a more developed and just country.”

When he talks about politics in the most tangible everyday terms, as a matter of whether people can afford beer and coffee and whether they have time to catch a soccer game, there’s nothing affected about it. And when he wants to, he can be bitterly eloquent, as in the passage in his letter to the Labour Party where he describes “austerity” as “the magic and wretched word that the rich everywhere use to attack the rights and achievements of the working class.” The picture he draws is global: “‘We need to save resources, cut costs,’ they say, as they disassemble the state and become ever richer while the poor become ever poorer. So it is in the United Kingdom, so it is once again in Brazil.”

In a prison interview, the American journalist Glenn Greenwald asked Lula a simple question: “Why is this happening?” The immediate context of that question was the rise of the far right in Latin America, but in his answer Lula threaded together the situation there with the election of Trump in the United States. He quoted the Mozambican writer Mia Cuoto, who said that, “In times of terror, we choose monsters to protect us.”

No doubt some readers with different takes on Brazil will accuse us of glorifying the record of Lula and the PT. To be clear, there are real problems with both and legitimate criticisms to be made — just as there are with all political actors who have real world political power. The fact remains that, in the words of journalist and international relations analyst Pepe Escobar, “Lula is Brazil’s only possible factor of stability. He’s ready, has an agenda not only for the nation but the world.”

Given his accomplishments and his unjust imprisonment, it would be enough to demand his release so he could hit the lecture circuit and spend time with his family. But as he’s made clear in interview after interview, in the media blitz he’s done after the authorities finally let him talk to journalists after a year of enforced silence, that he has thought deeply and strategically about the plague that afflicts Brazil and the United States and is metastasizing across the globe. It’s clear that Bernie is listening — and that he’s willing to challenge the foreign policy consensus that continues to support repressive right-wing governments in Latin America and across the globe.

None of the other candidates, even the ones ones who have tried the hardest to blur the lines between Sanders’ agenda and their own liberal worldview, have displayed the same clarity. Even the most moderate presidential candidates, if they are sincere about their concerns about democracy and climate, should be loudly and proudly saying, “Lula livre.”