Brazilian President Luiz Inacio Lula da Silva and right-wing Senator Flavio Bolsonaro wrapped up their presidential campaigns on Saturday, each expressing confidence in victory ahead of Sunday's first-round vote.

Lula, 80, closed his campaign with a march through Rio de Janeiro between two locations symbolic of Brazil's fight for democracy during the 1964–1985 military dictatorship. The march set off from the Candelária church, where more than a million people gathered in 1984 to demand direct presidential elections, and moved south toward Cinelândia, the site of a major pro-democracy protest in 1968.

His campaign also held a closing rally in Sao Paulo, Brazil's economic powerhouse, which his team described as drawing a record crowd.

"Tomorrow, we're going to win the elections in the first round," Lula told supporters. He framed the vote as a choice between "democracy and barbarism" and pledged to "defeat the far right."

Speaking ahead of the Rio march, Lula said he had decided to seek a fourth term because he believed only he could prevent his rival's family from returning to power. "If it weren't for me standing up to these fascists they'd easily win another election. I'm the one standing in their way," he said on a popular podcast called Flow, adding: "It's either me, or it's barbarism."

"What's at stake is not the victory of one man, it is the victory of an idea, it's the victory of democracy," Lula said after the Rio march began.

He also addressed concerns over foreign interference, vowing: "No gringo is going to lay a finger on Brazil's things," in an indirect reference to claims that the Trump administration is seeking to influence the vote in Bolsonaro's favour.

Flavio Bolsonaro, 45, led a motorcycle caravan through towns in Sao Paulo state before holding a rally in Rio de Janeiro. "I am convinced that everything is in place for us to win this election in the first round," he said. He was photographed at his rally holding a portrait of his father, former President Jair Bolsonaro.

Flavio Bolsonaro is the son of Jair Bolsonaro, 71, a close ally of US President Donald Trump. The former president is serving a 27-year prison sentence for attempting to overturn his 2022 election loss to Lula.

Flavio Bolsonaro has pledged to seek his father's release from prison if elected. He has also echoed his father's unsubstantiated claims questioning the reliability of Brazil's electronic voting system, a stance analysts say could be laying the groundwork to contest the result if he loses.

Trump has not formally endorsed Bolsonaro but has said he is watching the election "very closely." Lula's supporters have cited this as evidence of Washington attempting to interfere in the vote, while some Bolsonaro supporters say they would welcome US pressure if it helped force change at home.

Polls released on Saturday suggested Lula still held a lead, but that it was narrowing, with neither candidate likely to win outright on Sunday. Such an outcome would send the race to a run-off on October 25, a contest polls suggest would also be close. The race is considerably tighter than Lula's 2022 victory, when he defeated the elder Bolsonaro by less than two percentage points.

The Bolsonaro campaign has also faced scrutiny over a film-funding scandal. Flavio Bolsonaro is under investigation over financing for Dark Horse, a biopic about his father bankrolled by a jailed banker linked to one of Brazil's biggest financial scandals. Brazil's Supreme Court authorised federal police in April to investigate whether Flavio Bolsonaro made defamatory statements about Lula.

Many Brazilian democrats fear that a Bolsonaro victory could lead to the release of his father and fellow coup plotters from prison, and to efforts to weaken the country's democratic institutions.

"This is the most important election of our lives," said Marcelo Freixo, a politician from Lula's Workers' Party running for a congressional seat. "We spent 21 years living under a really harsh dictatorship. We fought so hard to attain our democratic institutions. And a victory for the Bolsonaro family — a family that always openly defended the dictatorship and tried to stage a coup — would spell the end for our democratic process and institutions."

Among those who attended Friday's pro-Lula rally in Rio, described as the city's largest leftwing protest in years, was Noni Ostrower, 74, who carried a homemade banner reading "Democracy Is Valuable." "I'm the daughter of two refugees from Nazism. They came to Brazil from Germany because of this," she said. "I absolutely do not want to see fascism return to Brazil — it would be a tragedy for the country."

Beyond the presidency, Brazil's nearly 160 million registered voters will also choose lawmakers, governors and senators on Sunday.