On the afternoon of September 19, New York Mayor Zohran Mamdani stood in front of a wastewater treatment plant at Hunts Point in the Bronx and told a group of visiting international mayors that it offered one of the best views in New York City. This was an illustration of Mamdani’s focus on the day-to-day mechanics of city government—sewage, buses, and potholes—and an argument he has been making throughout this year that the socialist left’s credibility will be rebuilt by proving that government can still make people’s lives easier.

Standing with him were the mayors of Helsinki, Barcelona, and Rome, who were part of the group of mayors and city leaders in New York over the weekend for the Urban 20, or U20, a summit of cities from G20 nations. On the sidelines of the summit, Mamdani hosted several left-wing mayors, taking them on a bus tour of New York City and showing them public housing in Brownsville. Mamdani’s office said his meetings with the mayors focused on finding solutions to housing, climate, and migration issues.

Throughout the weekend, it became clear that Mamdani’s pitch for a government that makes life easier for residents has resonated with his international counterparts. At the U20 summit on September 20, Mamdani argued that the left should reclaim phrases like “quality of life,” “efficiency,” and “waste” from the right. “If you are staring at an example of social disorder or social inefficiency, and the left refuses to explain either why it has happened or how they will fix it, then the right gets to point at someone in the immediate area and say, ‘That’s who did it,’” Mamdani said.

The same day, Mamdani said that the movement that made him mayor of New York extends far beyond the city and aims to address the crises of our times—the affordability crisis and the mass migration of millions of people due to climate change and instability. “Those fleeing war, genocide, flood, famine and instability should not be turned away but should be welcomed.… Each of us holds a shared responsibility to provide all our people with opportunity and to view migration not as an obstacle to a city’s success, but, frankly, as fundamental to that success,” Mamdani said.

Earlier this summer, the FIFA World Cup gave the soccer-fan mayor a chance to showcase his idea of a multicultural city in the face of threats from Washington. Even as FIFA priced ordinary fans out of the games, Mamdani pushed FIFA for cheaper tickets and opened up the city for pickup soccer games through the night. On game days in the New York area, Mamdani uploaded direct-to-camera videos in which he spoke about figures like Sócrates, a Brazilian legend whose club, Corinthians, opposed Brazil’s military dictatorship in the 1980s. In another video, he mentioned Brian Clough, the legendary English manager whose Derby County team stood on the picket lines during the 1972 miners’ strike.

The same political instincts were on display again this week as world leaders descended on New York. Mamdani met with Rome Mayor Roberto Gualtieri to discuss housing policy and with Mexico City Mayor Clara Brugada to hand out flyers to delivery workers informing them of their rights under local labor laws. He exchanged soccer jerseys with Brazilian President Luiz Inácio Lula da Silva, who is in a tight reelection fight against Senator Flávio Bolsonaro, the son of former president Jair Bolsonaro. And on September 22, Mamdani visited a public school with Norwegian Prime Minister Jonas Gahr Støre to discuss AI’s growing presence in classrooms. It is an area of interest for both leaders as New York followed Norway in restricting generative AI for younger students.

Mamdani’s convening of world leaders coincided with the surprise Berlin election win for Elif Eralp, the daughter of Turkish immigrants, who led Germany’s Left Party, Die Linke, to its strongest-ever result in the city on a platform focusing squarely on cost of living and housing. Outlets have already run headlines crediting the influence of Mamdani’s campaign in Berlin after a delegation of Die Linke met with Mamdani’s advisers in New York recently. It has also emerged that political organizations in Europe have studied the canvassing operation that propelled the New York mayor to his election win.

These exchanges have placed Mamdani at the center of the international left as it tries to fight the economic order that has worsened mass migration and made cities inhospitable. “At a time of division and retreat, our cities are choosing cooperation,” Mamdani said ahead of the U20 event. In his closing remarks on September 20, he added, “Familiarity allows us to communicate effectively and openly. It facilitates the lending of policy, the sharing of lessons learned, the exchange of ideas. A transit win in one city informs a newfound ambition in another. A public health success here becomes a blueprint there. That is what familiarity can do. That is the practice of solidarity in action.”