Luiz Inácio Lula da Silva has won Brazil’s presidential election by a whisker, but with incumbent Jair Bolsonaro still not conceding defeat there were concerns the far-right contender might challenge the result.

According to the country’s election authority, Lula secured 50.8 percent of the vote compared with 49.2 percent for Bolsonaro on Sunday.

“Today the only winner is the Brazilian people,” da Silva told the crowds gathered at a Sao Paulo hotel. “This isn’t a victory of mine or the Workers’ Party, nor the parties that supported me in campaign. It’s the victory of a democratic movement that formed above political parties, personal interests and ideologies so that democracy came out victorious.”

Bolsonaro had been leading throughout the first half of the vote count, but as soon as Lula took the lead, the streets of Sao Paulo’s city centre filled with the sound of cars honking their horns.

People in Rio de Janeiro’s Ipanema neighbourhood could be heard shouting, “It turned!”

“He’s the best for the poor, especially in the countryside,” said retired government worker Luiz Carlos Gomes, 65, who comes from Maranhao state in the poor northeast region. “We were always starving before him.”

The vote also marked the first time that the sitting president failed to win re-election. Just over two million votes separated the two candidates; the previous closest race, in 2014, was decided by a margin of roughly 3.5 million votes.

Bolsonaro silent

It is a tradition in Brazil for the losing candidate to speak first and accept the election loss, but hours after the authorities had named Lula the winner, Bolsonaro had made no public statement on the outcome.

“So far, Bolsonaro has not called me to recognise my victory, and I don’t know if he will call or if he will recognise my victory,” Lula told tens of thousands of jubilant supporters celebrating his win on Sao Paulo’s Paulista Ave.

The 67-year-old Bolsonaro has previously claimed, without proof, that the voting system was at risk of fraud.

Electoral authorities are bracing for him to dispute the outcome, separate sources told Reuters, and had made security preparations in case of protests by his supporters.

The 2022 election served as a referendum on two starkly different — and vehemently opposed — visions for Brazil’s future.

Lula promised more social and environmental responsibility, while Bolsonaro campaigned to consolidate a sharp rightward turn in Brazilian politics after a presidency that witnessed one of the world’s deadliest outbreaks of COVID-19 and widespread deforestation in the Amazon.

Guilherme Casaroes, from the Brazilian Center for International Relations, said the atmosphere in Sao Paulo felt like it did when Lula was first elected in 2002.

“It was more an election of hope back then. Now, I have the feeling that many people are celebrating the end of a very dark period. I think everyone knows it’s an uphill battle, but I think people are very excited to see what Lula will do,” Casaroes told Al Jazeera.

“I will govern for 215 million Brazilians, and not just for those who voted for me,” Lula said at his campaign headquarters. “There are not two Brazils. We are one country, one people, one great nation.”

Lula arrived at the Sao Paulo rally shortly after 8:00pm local time (23:00 GMT), waving from the sunroof of a car. Ecstatic supporters near Paulista Avenue waited for him, chanting slogans and drinking champagne.

Oliver Stuenkel, a professor of international relations, said Lula will need to work hard on reconciliation given the stark divide.

“Basically 50 percent of Brazilians are very afraid his return to power. This is a very polarised country, it’s a frustrated country, it’s a more poorer country. A lot of people may question the legitimacy of this election. I think it’s a volatile moment now, and Lula will have to choose his words very carefully,” Stuenkel, from the Fundação Getulio Vargas (FGV) in Sao Paulo, told Al Jazeera.

Congratulations pour in

Bolsonaro’s four years in office were marked by proclaimed conservatism and the defence of so-called traditional Christian values. He claimed his rival’s return to power would usher in communism, the legalisation of drugs, abortion and the persecution of churches — none of which happened during Lula’s earlier eight years in office.

Leaders from around the region and elsewhere in the world, congratulated Lula on his win, with US President Joe Biden noting in a statement that the elections had been “free, fair, and credible” while Canadian Prime Minister Justin Trudeau said he was looking forward to working with Lula to protect the environment.

Fellow left-wing leaders including Argentina’s President  Alberto Fernandez and Chile’s President Gabriel Boric Font welcomed Lula’s victory with Fernandez saying it opened “a new era for the history of Latin America” and heralded a time of hope.

Thomas Traumann, an independent political analyst, compared the election results with US President Joe Biden’s 2020 victory, noting Brazil’s divisions.

“The huge challenge that Lula has will be to pacify the country,” said Traumann. “People are not only polarised on political matters, but also have different values, identity and opinions. What’s more they don’t care what the other side’s values, identities and opinions are.”

Lula is credited with building an extensive social welfare programme during his previous period in office, helping lift tens of millions into the middle class, as well as presiding over an economic boom. He left office with an approval rating above 80 percent.

But he is also remembered for his administration’s involvement in vast corruption revealed by sprawling investigations. Da Silva’s arrest in 2018 kept him out of that year’s race against Bolsonaro, a fringe legislator at the time.