has claimed he is the only thing standing in the way of far-right “fascists” reclaiming power, as he led a huge rally through the streets of Rio ahead of Sunday’s crunch election.

Speaking on the eve of the demonstration, the 80-year-old leftwinger said he had decided to seek a historic fourth term because he believed only he could prevent the family of his rightwing rival, Flávio Bolsonaro, returning to government.

“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,” Lula told a popular podcast called Flow before adding: “It’s either me, or it’s barbarism.”Hours later, Lula flew to Rio, staging what his team called a “victory march” between two highly symbolic downtown locations that played an important role in Brazil’s fight for democracy during the 1964-1985 military dictatorship.

“What’s at stake is not the victory of one man, it is the victory of an idea, it’s the victory of democracy,” Brazil’s president said after the parade set off from the Candelária church. The church is the location where more than a million people, including Lula, famously gathered in 1984 to demand direct presidential elections.

Lula, who was among those who spoke at that historic demo when he was an up-and-coming politician in his 30s, added: “Either we consolidate democracy, or we will lose it.”From Candelária, a sea of red-clad Lula supporters marched a mile south towards Cinelândia, the scene of an equally well-known pro-democracy protest in 1968 called the March of the Hundred Thousand.

“No gringo is going to lay a finger on Brazil’s things,” vowed Lula, in an indirect reference to claims Donald Trump’s administration is seeking to sway the vote in Bolsonaro’s favour with a campaign of economic and diplomatic pressure.

The decision to hold Friday’s rally between two such politically charged places spoke to how this year’s election has stirred up renewed fears over the future of Latin America’s biggest democracy.

Election-eve polls suggest Lula holds only a slender lead over his adversary, whose father, the ex-president Jair Bolsonaro, is serving a 27-year sentence for plotting a failed coup after Lula beat him in the 2022 election.

Many Brazilian democrats fear that if 45-year-old Bolsonaro wins this year’s election, he will move quickly to free his father and his fellow coup-plotters from jail – and then set about dismantling and co-opting the country’s democratic institutions, such as the supreme court.

“This is the most important election of our lives – and we have to do everything we can to win,” said Marcelo Freixo, a politician from Lula’s Worker’s party (PT) who is running for a seat in congress.

Freixo warned: “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.”

Valmir Aleixo, a 55-year-old history teacher who was one of thousands of people who joined Friday’s pro-Lula demo, said: “This is [a choice] between democracy and the savagery of far-right fascism. This is perhaps the most important election since the return of democracy in the 80s.”Noni Ostrower, 74, came to what was Rio’s largest leftwing protest in years carrying a homemade banner that read: “Democracy Is Valuable”.

“I’m the daughter of two refugees from nazism. They came to Brazil from Germany because of this,” Ostrower said. “I was born here in Brazil … and today I have grandchildren and I absolutely do not want to see fascism return to Brazil – it would be a tragedy for the country. That’s why I’m here today.”During the campaign, Flávio Bolsonaro has vowed to pardon his 71-year-old father if elected, with some speculating Jair Bolsonaro could even become a minister. His brother, Eduardo Bolsonaro, a radical former congressman with ties to Trump’s Maga movement, reputedly hopes to become foreign minister. Flávio Bolsonaro has announced plans to appoint five firmly conservative supreme court judges.

Luiz Eduardo Soares, a prominent anthropologist and writer, said he feared what might happen if the Bolsonaro clan managed to reclaim power.

“I think these elections could be the last ones in my life, for my generation … What was done over the course of 10 years in Hungary, [Bolsonaro] will do in two,” Soares predicted in reference to the European country’s transformation into an “electoral autocracy” under its former prime minister, Viktor Orbán.

Diogo Nogueira, a famous samba singer who came to the rally wearing his trademark panama hat, said: “We need to win in the first round so we don’t allow this type of people to get back into government. If they do get back in, it won’t just be a problem for four years, but for 10 or 20.”Polls suggest the election is likely to go to a second round runoff between Lula and Bolsonaro on 25 October, with Lula expected to secure about 45% of votes on Sunday and Bolsonaro 40%, according to the Datafolha pollster. But at Friday’s rally Lula claimed he could pull off a shock first-round win by claiming more than 50% of the vote.

In an online broadcast, Bolsonaro insisted his campaign would prevail. “Brazil is a few hours from deciding its future … for the next 30, 40, 50 years. It’s the end of an era. It’s the end of the Worker’s party era,” he claimed, asking undecided voters to back him to achieve that aim, even if they didn’t like him.