Trade between Argentina and Brazil reached US$31.2 billion in 2025, its highest level in 13 years, according to the Rosario Board of Trade. That sum looms over Brazil's election on Sunday, when Senator Flávio Bolsonaro, eldest son of former president Jair Bolsonaro, was due to face President Lula. For Argentine President Javier Milei, the vote could determine whether he gets a friendly neighbor, a frozen diplomatic relationship or a rival for Washington's attention.
The Trade Stakes
The figures favor Brazil. Argentina sent US$12.8 billion in goods across the border and bought US$18.4 billion from its neighbor, leaving a deficit of about US$5.7 billion. Cars, car parts, wheat and fuel make up much of the trade, Forbes Argentina reported. Tariffs, political fights and bad blood hit those sectors hardest.
The economic ties give both governments a practical reason to repair relations. A Bolsonaro victory could thaw the diplomatic freeze. If Lula wins, Milei would face a neighbor he has repeatedly insulted.
A Diplomatic Freeze
Milei didn't conceal his preference. On 25 July, he joined Flávio Bolsonaro's campaign launch in São Paulo. La Nación reported that Milei called Flávio a friend and Lula a "thief." Brazil downgraded its diplomatic representation in Buenos Aires in August, and neither ambassador had returned to post, according to La Nación.
Flávio has made overtures to Buenos Aires, too. In June, he promised Brazil would "return to being a brother to Argentina." His economic coordinator, Daniella Marques, said his plan draws on Milei's approach. He has also pledged that Brazil would join the Shield of the Americas, a U.S.-led security initiative Argentina already belongs to.
The Washington Question
Donald Trump complicates the picture. Political writer Mariano Obarrio published an analysis in the Argentine news site iProfesional on Saturday 3 October, drawing on sources in Argentina's foreign ministry. "If Bolsonaro wins, the United States will give more room to Bolsonaro than to Milei," one source told him. The reason, the source said, was scale: "Brazil weighs more as a country and because of the size of its economy."
Brazil has about 213 million people, more than four times Argentina's population, and Latin America's largest economy. Officials at the Casa Rosada, the presidential palace, told iProfesional: "They would love Bolsonaro to win, but 'worry' is not the word." The report said Milei was wary of intervening directly in the campaign and hadn't ruled out traveling to Brazil if Flávio Bolsonaro won the first round.
In a separate analysis, Argentine outlet TotalNews quoted Benjamin Gedan of the Stimson Center, a Washington think tank. Gedan, a former White House adviser on South America, called Flávio Bolsonaro "as MAGA as Milei" and said he was "equally committed" to becoming Washington's main South American ally.
Buenos Aires's concern reflects the judgment of unnamed officials, not a signal from Washington. Trump hadn't endorsed Flávio Bolsonaro, Time reported, though he called Brazil's vote very important. iProfesional described a possible double effect: Milei could gain a like-minded partner next door, while sharing Trump's attention with a much larger country.
Polls were due to close at 17:00 Brasília time, also 17:00 in Buenos Aires and 20:00 UTC. If no candidate won more than half of the valid votes, the top two would meet again on 25 October.
Why This Matters:
This story reaches beyond a campaign rivalry. Argentina runs a US$5.7 billion trade deficit with a neighbor whose government it has publicly insulted, and its leader's standing in Washington may hinge on events he can't control. From a market perspective, commercial relationships that support carmakers, grain exporters and fuel suppliers shouldn't hinge on personal feuds between presidents. A Bolsonaro win would bring a government that says it wants to borrow from Milei's economic approach and join a U.S.-led security initiative. A Lula win would keep the freeze in place. Either way, predictable relations between major trading partners matter more than any leader's political friendships. For now, fears in Buenos Aires remain the views of unnamed officials, not a position taken in Washington.