Brazilian voters head to the polls Sunday in a presidential contest that could test whether U.S. pressure on President Luiz Inácio Lula da Silva’s government helps his challenger, Flávio Bolsonaro, or strengthens Lula’s appeal as a defender of national sovereignty. Neither candidate is expected to win more than 50 per cent, making an Oct. 25 runoff a near certainty. An AtlasIntel/Bloomberg poll released Tuesday put Bolsonaro at 47.7 per cent and Lula at 47.6 per cent in a potential second round.

The close campaign has focused on the economy, crime and scandal. A probe into a prominent jailed banker found that he financed a new, laudatory biopic about former president Jair Bolsonaro at Flávio Bolsonaro’s request. Jair Bolsonaro, a right-wing firebrand and Flávio’s father, is serving a 27-year prison sentence for an attempted coup. Flávio has presented himself as a more moderate version of his father.

The United States has not formally endorsed Flávio Bolsonaro, but Washington is widely seen as preferring him. The Trump administration has clashed with Lula’s government on trade, Cuba and Venezuela, and has sought access to Brazil’s rare earth supplies. President Donald Trump is also personally close to the Bolsonaro family. At their request, the U.S. has applied pressure intended to weaken Lula’s government, prompting concern about further interference in the election.

That pressure campaign gathered force last summer. Eduardo Bolsonaro, Flávio’s brother, persuaded the Trump administration to impose 50 per cent tariffs on Brazilian imports and sanctions on a Brazilian Supreme Court judge, seeking to get Brazilian authorities to drop Jair Bolsonaro’s trial. Trump described the prosecution as a “witch-hunt.” White House Press Secretary Karoline Leavitt indicated the U.S. might use “military might” against Brazil over the case.

The sanctions and tariffs were later rolled back. In July, however, the U.S. imposed new tariffs totalling 37.5 per cent on Brazilian imports, citing unfair trade practices. It singled out Pix, Brazil’s popular payment transfer system. U.S. credit card companies such as Visa and Mastercard have objected to Pix because they miss out on transaction fees when people use it.

In May, the U.S. State Department classified two Brazilian criminal groups, Comando Vermelho (CV) and Primeiro Comando da Capital (PCC), as terrorist organizations. The decision was justified in part as a way to combat “narcoterrorism” in the region. Flávio Bolsonaro visited the Oval Office to urge Trump to classify the PCC and CV as terrorist organizations. “We’ve got to help these guys,” Trump told aides at the time.

The designation alarmed observers because Trump has repeatedly invoked “narcoterrorism” to justify lethal air strikes on alleged drug-smuggling boats and the kidnapping of Venezuelan President Nicolás Maduro. James Green, professor emeritus of Portuguese and Brazilian studies at Brown University, said the U.S. moves were met with apprehension in Brazil because they suggested Trump’s threats were more than bluster.

“Brazil did not want the U.S.’ imposition of this category on these criminal organizations because it opened the door for many ways in which the Trump administration could interfere in Brazilian internal politics,” Green told Responsible Statecraft. He added: “Even though they haven't overtly said, 'Oh, Flávio is my candidate,' they sent all these signals to indicate that that's who the United States wants to see elected.”

Gunther Rudzit, assistant professor of international relations at ESPM, a private university in São Paulo, said not every U.S. action was explicitly part of a plan to boost Bolsonaro’s candidacy. Taken together, though, he described them as “an attempt to shape the political environment in which the Brazilian election is taking place.”

Whether Washington would recognize a Lula victory is another concern. In a September press conference outside the State Department, Eduardo Bolsonaro suggested the U.S. “could perfectly well refuse to recognize the Brazilian elections.” Trump could find support from right-wing allies across the region if he took that approach. Right-wing parties are gaining ground in Argentina, Chile, Ecuador, Peru and Bolivia. Trump openly endorsed candidates in Colombia and Honduras, both of whom won their elections. “We have numerous people, Argentina, lots of people that I got elected,” Trump said last month.

Brazilian officials have responded to the prospect of U.S. interference. In August, Abin, Brazil’s intelligence agency, sent a report to key government agencies warning about possible interference in the election. Brazilian officials also denied visa requests for two State Department officials, saying the purpose of their visit was to discredit the integrity of Brazil’s electoral system.

Other U.S. actions have added pressure on Lula’s government. In July, the U.S. consulate in São Paulo took the unusual step of inviting conservative social media influencers to a roundtable on “freedom of expression and the digital environment.” The Guardian reported Thursday that the State Department plans to award $1 million to Brazilian groups opposing “judicial overreach and censorship by Brazil’s supreme court.” The phrase refers to Washington’s sanctions against Brazilian judge Alexandre de Moraes.

Lula’s Workers’ Party has asked the Supreme Court to investigate possible election interference by Rockbridge, a secretive political advocacy group backed by Silicon Valley investors, including Peter Thiel. People close to Bolsonaro proposed securing investment promises from Rockbridge and creating a “Technology Council” to advise the candidate. Proposed members included Palantir’s Shyam Sankar and Joe Lonsdale. A Rockbridge spokesperson told Intercept Brasil that none of the plans materialized.

The pressure campaign may not benefit Bolsonaro. Many Brazilians could see U.S. actions as an affront to national sovereignty and economic independence, themes Lula has championed since his time as a labour union leader in the 1970s and 1980s. After the Trump administration imposed tariffs on Brazil last July, Lula’s approval rating rose above 50 per cent, up from 47 per cent the month before.

Camila Feix Vidal, professor of international relations at the Federal University of Santa Catarina, said the “U.S. actions towards Brazil - particularly the tariffs, interest in rare earth reserves, and the criticisms of Pix - all fostered a nationalist spirit in Brazil, at least initially.” Lula has made U.S. tactics a central part of his campaign. A new Lula campaign advertisement scheduled to air Friday says: “Flávio Bolsonaro is Trump’s candidate and what Trump wants is to colonize Brazil, take our riches, steal our future and leave us in the dust.”

In an interview this week, Lula said: “I told Trump: 'Don't interfere in the Brazilian elections because otherwise you'll lose the elections.’” Rudzit said Flávio Bolsonaro has called for U.S. tariffs to be suspended because of concern about a nationalist backlash. “The closer the association between external pressure and the Bolsonaro family, the easier it is for Lula to present himself not simply as the incumbent defending his administration, but as the president defending national autonomy,” he said.

Rudzit said economic pressure could strengthen Lula in the short term by generating nationalist resistance, but the resulting costs could eventually reduce his chances at the ballot box. “Much depends on who Brazilian voters ultimately blame for those costs: Washington, the Bolsonaro family, Lula’s government, or some combination of them,” he said.

Even a Bolsonaro victory might not give Trump an ally who readily follows U.S. demands. Quincy Institute non-resident fellows Andre Pagliarini and Feliciano de Sá Guimarães argued in a recent policy brief that a Bolsonaro presidency could remain constrained, particularly on China. “A Brazilian government visibly inclined toward the United States would face its own constraints,” they wrote. “Flavio Bolsonaro’s father discovered as much during his presidency, when an initially hostile posture toward Beijing gave way to the practical demands of governing a country whose economic relationship with China could not simply be subordinated to ideological posturing.”

With a slim margin expected whichever candidate wins, the election could face a contested aftermath.

Based on reporting by Responsible Statecraft.