Brazil was on a knife-edge Sunday as voters chose between far-right incumbent Jair Bolsonaro and his leftist arch-rival, Luiz Inacio Lula da Silva, in a presidential election seen as too close to call.

The runoff election caps a dirty and divisive campaign that has left the nation of 215 million people deeply split between supporters of conservative ex-army captain Bolsonaro, those of charismatic ex-metalworker Lula, and many others more or less equally disgusted by both.

"I think this has been the best government Brazil has ever had," said Afro-Brazilian lawyer Eliane de Oliveira, 61, who voted for Bolsonaro in Rio de Janeiro's Copacabana neighborhood, saying she was happy to have a government "that is not corrupt", in a dig at the graft-tainted Lula.

Standing nearby, physical education teacher Gustavo Souza voted for Lula and "the hope of improving people's lives."

Like many, he said he was "scared" about the outcome, reflecting fears that Bolsonaro would not accept the result after months of attacking the electoral system.

"People have become so radical. They will need some maturity... or it will turn into the third or fourth world war," he said, laughing nervously.

'Brazil will be victorious'

Lula, 77, narrowly won the first-round election on October 2, and enters the finale the slight favorite with 52% of voter support to 48% for Bolsonaro, according to a final poll from the Datafolha institute Saturday.

However, Bolsonaro, 67, performed better than expected last time around, and the result this time is anyone's guess.

The president cast his ballot wearing a T-shirt in the yellow-and-green of the Brazilian flag - a symbol he has adopted as his own.

"God willing, we'll be victorious later today. Or even better, Brazil will be victorious," he said, grinning as he greeted supporters in Rio de Janeiro's Vila Militar neighborhood.

He then headed to the airport to snap pictures and take a ride in the presidential helicopter with players for Flamengo, Brazil's most popular football team, who were fresh off winning the South American club championships in Ecuador Friday evening.

Lula voted in Sao Bernardo do Campo, the southeastern city where he got his start as a union leader, wearing a white guayabera-style shirt and surrounded by white-clad allies.

He said he was "confident in the victory of democracy," and that he would seek to "restore peace" in a divided nation if elected.

Democracy, Amazon

The electoral showdown caps months of mud-slinging and personal attacks, in a campaign plagued by disinformation.

The election has global ramifications: Conservationists believe the result could seal the fate of the stricken Amazon rainforest, pushed to the brink by fires and deforestation that have surged under Bolsonaro.

However, for Brazilians, issues of poverty, hunger, corruption and traditional values are top of mind.

Waiting at his polling station in Sao Paulo, psychologist Marcelo Silveira Curi, 35, said he disliked both candidates but was reluctantly voting for Lula.

"He's not ideal, but he's the option if you oppose this government," he told AFP.

Politically split couple Elisete and Alex Silveira, who have been married for 27 years, said the tension tearing Brazil apart has invaded their home, as they voted in the capital, Brasilia - Elisete, 46, in pro-Lula red, and Alex, 50, in pro-Bolsonaro yellow and green.

"We agreed on a resolution: no talking politics at home, out of the love we have for each other," laughed Elisete, a dance teacher.

Will Bolsonaro cry foul?

One of the main questions hanging over the poll has been if Bolsonaro - often dubbed the "Tropical Trump" - will accept a loss.

On Friday night he pledged to respect the election, though possible accusations of rigging and a backlash from his supporters loom large.

Bolsonaro came under fire for his disastrous handling of the Covid-19 pandemic, which left more than 680,000 dead in Brazil, as well as his vitriolic style and disdain for political correctness.

However, in recent months, falling unemployment figures, slowing inflation and a recovering economy have given him a boost.

His core supporters - the business sector, anti-corruption voters and the powerful "Bibles, bullets and beef" coalition - love his gloves-off style and focus on conservative values.

Comeback kid

Lula was the country's most popular president when he left office, helping to lift millions out of poverty with his social programs.

But he then became mired in a massive corruption scandal and was jailed for 18 months, before his convictions were thrown out last year. The Supreme Court found the lead judge was biased, but Lula was not exonerated.

If he wins, he faces a hostile Congress dominated by Bolsonaro lawmakers and allies.

Brazil's 156 million voters will cast their ballots until 5pm (2000 GMT). The result of the electronic vote is expected in a matter of hours.