RIO DE JANEIRO — Brazil pushed for concerted action to alleviate hunger Monday as it hosted a summit of the Group of 20 leading economies amid global uncertainty over two major wars and U.S. President- elect Donald Trump.

Brazilian President Luiz Inácio Lula da Silva welcomed foreign leaders to Rio de Janeiro’s modern art museum Monday and delivered an opening address that focused on fighting food insecurity.

“It is for those of us here, around this table, to face the undelayable task of ending this stain that shames humanity,” Lula told his colleagues. “That will be our biggest legacy.”

Heightened global tensions and uncertainty about an incoming Trump administration had tempered expectations for a strongly worded statement addressing the conflicts in the Middle East and between Russia and Ukraine. Further dimming prospects, G20 officials said Argentina’s negotiators have started challenging some of the draft language.

That has left experts anticipating a final document focused on social issues like the eradication of hunger — one of Brazil’s priorities — even if it still aims to include at least a mention of the wars.

“Brazilian diplomacy has been strongly engaged in this task, but to expect a substantively strong and consensual declaration in a year like 2024 with two serious international conflicts is to set the bar very high,” said Cristiane Lucena Carneiro, an international relations professor at the University of Sao Paulo.

After Lula thwarted far-right President Jair Bolsonaro’s reelection bid in 2022, there was some excitement in the international community at the prospect of the leftist leader and savvy diplomat hosting the G20. Bolsonaro had little interest in international summits, let foreign policy be guided by ideology and clashed with several leaders, including French President Emmanuel Macron. Lula took office and often quoted a catchphrase: “Brazil is back.”

Under Lula, Brazil has reverted to its decades-old principle of nonalignment to carve out a policy that best safeguards its interests in an increasingly multipolar world.

Two officials from Brazil and one from another G20 nation say Argentina is standing in the way of a joint declaration. Two of them said Argentine negotiators have raised several objections to the draft, most vehemently opposing a clause calling for a global tax on the superrich — which they had accepted in July — and one promoting gender equality.

Last month, Argentina opposed a declaration of the G20 working group on female empowerment, preventing consensus. While Lula received heads of state Monday with smiles and warm embraces, he and Argentina’s right-wing president, Javier Milei, stood at arms’ length while briefly shaking hands. Milei is an avid Trump supporter.

Trump’s win in the U.S. election this month and the imminent return of an “America First” doctrine may also hamper the diplomatic spirit needed for broad agreement on divisive issues, analysts said.

Ambassador Mauricio Lyrio, Brazil’s key negotiator at G20, had told reporters that Lula’s launch of a global alliance Monday against hunger and poverty is just as important as the final statement. As of Monday, 82 nations had signed on to the plan, Brazil’s government said. It is also backed by such organizations as the Rockefeller Foundation and the Bill & Melinda Gates Foundation.

A demonstration Sunday on Rio’s Copacabana beach featured 733 empty plates spread across the sand to represent the 733 million people who went hungry in 2023, according to U.N. data.

“Brazil wanted a global deal to fight poverty, a project to finance green transition and some consensus over a global tax for the superrich. Only the first one has survived,” said Thomas Traumann, a former government minister and a political consultant based in Rio.

Be that as it may, Lula reiterated his call for a tax on billionaires at the start of leaders’ afternoon session.

“Taxation of 2% on the total assets of superrich individuals could generate funds of about $250 billion per year to be invested in facing up to social and environmental challenges all over the world,” he said.

President Joe Biden attended the summit after a stop in Lima for the Asia-Pacific Economic Cooperation forum. He also traveled over the weekend to Manaus, a city in Brazil’s Amazon rainforest. It was the first time a sitting American president set foot in the Amazon.

On Sunday, the White House announced a second $50 million contribution to the Amazon Fund, the most significant international effort to preserve the rainforest. Biden’s administration announced plans last year to give $500 million.