Brazilian President Jair Bolsonaro has rallied alongside tens of thousands of his supporters at a military parade in the country’s capital, brushing off criticism that the far-right leader is using the Independence Day festivities to bolster his re-election bid.

Brazil remains tense just weeks ahead of the October 2 vote, which most opinion polls have shown will see Bolsonaro defeated by his rival, former left-wing President Luiz Inacio Lula da Silva.

After taking in a giant procession of soldiers, tanks and tractors down the Esplanade of Ministries in Brasilia on Wednesday, Bolsonaro gave a fiery speech to a sea of green-and-yellow-clad supporters.

“Our battle is a fight between good and evil,” the former army captain told the crowd, amid cries of “Lula, you thief” and banners calling for military intervention in Brazil’s Supreme Court.

In recent months, Bolsonaro has repeatedly taken aim at leading Supreme Court justices and alleged – without providing any evidence – that Brazil’s electronic voting system is vulnerable to widespread fraud.

A massive procession of soldiers, tanks and tractors made its way down the Esplanade of Ministries in Brasilia

Legal experts have rejected that allegation, while the president’s critics accuse him of sowing doubt ahead of the election in order to dispute the results, as was done by former US President Donald Trump, whom Bolsonaro has emulated.

“Bolsonaro, activate the military to depose the Supreme Court,” said one banner in Brasilia, carried by 64-year-old supporter Suely Ferreira. “Our country is being ruined by the [high] court’s dictatorship,” she told the AFP news agency.

“We love our president. Everyone I know supports him. He’s going to win. There’s no way he could lose.”

The president’s attacks on the voting system have stirred calls for a military coup from some of his more radical backers, fuelling concerns that the South American nation could see election-related violence.

“Bolsonaro and his supporters have built this up into the most important day of the whole campaign. So he’ll have to deliver some kind of red meat,” said Brian Winter, vice president for policy at the Americas Society/Council of the Americas.

“But everyone wants to know if he’ll cross that line and create a genuine institutional crisis.”

During his speech in Brasilia, Bolsonaro also denounced polls from leading public opinion institute Datafolha – whose latest shows him trailing Lula 45 percent to 32 percent – as “a lie”.

Lula, who has urged Brazilians to support him at the polls in order to “build an alternative path to the incompetence and authoritarianism that govern us”, apparently plans to keep a low profile on Wednesday.

Tens of thousands of Bolsonaro supporters turned out for an Independence Day rally in Brasilia

The former president, who led Brazil from 2003 to 2010, has rallies scheduled for Thursday and a meeting with Evangelicals, a key voting bloc, on Friday.

But he did take to Twitter to accuse Bolsonaro of hijacking the bicentennial festivities. “September 7 should be a day of love and unity for Brazil. Unfortunately, that’s not what’s happening today,” Lula wrote. “But I have faith Brazil will reclaim its flag, its sovereignty and its democracy.”

Meanwhile, Bolsonaro went later on Wednesday to Rio de Janeiro, where his backers flooded the avenue along the city’s iconic Copacabana beach as throngs prepared massive motorcycle and jet-ski processions.

The Bolsonaro camp has been highly active on social networks, urging supporters to turn out en masse for the day.

“President Jair Bolsonaro literally moved heaven and earth today … He’s trying to show his force and his popularity on the streets,” Al Jazeera’s Monica Yanakiew reported from Rio.

In contrast, the other presidential candidates have not wanted to transform “what is supposed to be a national celebration into a partisan event” – something they criticised Bolsonaro for, Yanakiew said. “But for Bolsonaro, it’s very important because he is still trailing behind Lula by two digits.”

Experts say political tensions are rising in Brazil ahead of the October 2 vote

On Independence Day last year, Bolsonaro also struck a defiant tone, saying that “only God” could remove him from office. “Only God will take me out of Brasilia,” he told a crowd of more than 100,000 supporters in Sao Paulo.

Bolsonaro’s congressman son Eduardo raised eyebrows on Twitter on Monday by calling on Brazilians “who have legally purchased guns” – a contingent his father has sought to expand with aggressive gun-control rollbacks – to enlist as “volunteers for Bolsonaro”.

Such comments have added to the fears of violence.

“September 7 will be politicised by definition this year, coming in the home stretch of the campaign,” political scientist Paulo Baia of the Federal University of Rio de Janeiro (UFRJ) told AFP. “It will be tense and potentially violent.”