New York City’s left-wing Mayor Zohran Mamdani congratulated Brazilian president Lula Inacio de la Silva on his questionable reelection victory on Sunday by quoting a Marxist slogan: “The people united will never be defeated!”

Lula narrowly won the second round of the Brazilian presidential election on Sunday, after losing the first round to Sen. Flávio Bolsonaro by a little over two points. The outcome has been challenged because a judge loyal to Lula intervened at the last minute to keep the polls open for an extra two hours in Lula’s northeastern electoral stronghold of Bahia. As of Monday morning, Bolsonaro has not conceded the race.

Left-wing celebrities and political figures around the world nevertheless leaped to congratulate Lula for winning reelection to a historic fourth term, even as much of Latin America has been leaning to the right.

Mamdani extended his congratulations by quoting the title of “The People United Will Never Be Defeated,” a Marxist protest anthem from the 1970s.

The song was written by Chilean pianist Sergio Ortega as the government of Communist-sympathizing President Salvador Allende was tottering on the edge of a coup led by Gen. Augusto Pinochet. The stage for the coup was set when Allende nationalized the Chilean mining industry, leading to a series of debilitating nationwide strikes by workers.

Pinochet overthrew Allende in September 1973 and went on to rule Chile for 17 years. Allende died under somewhat unclear circumstances during the coup. A Chilean court investigating his death ruled in 2012 that he committed suicide as Pinochet’s troops were storming the presidential palace, using an AK-47 rifle gifted to him by Fidel Castro. Many leftists, including Castro, disputed that finding and insisted Allende died in a heroic last-stand gun battle with the invading soldiers.

The fall of Allende, and rise of Pinochet, have been viewed through very different lenses by people of the left and right over the ensuing decades. For the left, Allende became a martyr to socialism and Ortega’s song became an anthem for the perseverance and righteousness of the worldwide communist movement.

Percussionist Carlos Quezada, who played in Ortega’s band and was exiled to France after the Pinochet coup, reminisced about “The United People Will Never Be Defeated” in a December 2019 BBC interview.

“It was very exciting. We defended ourselves through songs, it was our only possibility. We felt that we had the responsibility to raise awareness in people, through music, to avoid the hell that came a few months later anyway,” he said.

Quezada said the song grew in popularity among the European left during his exile, as the band kept playing it during their concerts, often on request. The song has figured in many street demonstrations over the years, including the destructive “Yellow Vest Movement” protests in France from 2018 to 2020, a movement that is making a comeback through the chaotic vandalism in France today.

“They always ask us to end this song; I’ve been in the band for 50 years and I think I’ve sung it more than a thousand times,” Quezada said.