For voters, Bolsonaro and Haddad represent starkly different visions for the future. The second ballot is on October 28. "I have the utmost respect and admiration for the work they did", said Mr. Haddad.
"This is a victory for honest people who want the best for Brazil", said Bianca Santos, a 40-year-old psychologist who gathered outside a hotel where Bolsonaro was watching the returns. Bolsonaro's rejection rate stood at 44 percent. The left-wing fear mongering lead to an assassination attempt on the life of Bolsonaro who was stabbed at a campaign event that nearly took his life.
Some voters - particularly women - wore "Not Him" slogans to polling stations, declaring their fierce opposition to Bolsonaro.
Ciro Gomes, another centre-left candidate, came in third place on Sunday with about 12.5 percent of the vote.
The election was a seismic shift for this nation of more than 200 million people, where the left has won the past four elections but deep divisions have opened in the wake of a massive corruption scandal and the 2016 impeachment of then-President Dilma Rousseff.
The Brazilian real has surged on the results. Bolsonaro has pledged to roll back gun controls and make it easier for police to kill.
"This was a great victory, considering we had no television time, a party that is still very small with no campaign money and I was in hospital for 30 days", he said in video streamed live over social media. He was also stabbed last month, keeping him off the campaign trial for much of the lead-up to Sunday's election.More news: McConnell now open to high court nomination in election year
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Haddad, though, has his own challenge.
Jana Tessarolo Clemente, a 46-year-old veterinarian from Sao Paulo said she voted for the former army captain "because we're against the Workers' Party more than for Bolsonaro".
Brazilian markets had already rallied in recent weeks as polls showed a consistent lead for Bolsonaro, a longtime statist who made a late conversion to orthodox economic policies after tapping a University of Chicago-trained banker as his main economic adviser.
During Brazil's last election, in 2014, the PSL won one seat in the lower house.
"We're going to have a huge caucus, perfectly governable, to pass the bills that the society is demanding - to conclude the reforms that are underway", Bivar said, referring to stalled efforts to trim public pensions and close a budget deficit.
"Not all of Bolsonaro voters are bigots or homophobic, a lot of them vote for Bolsonaro despite what he's saying. he has mobilised a latent and existing discontent". A quarter of the voters are in the less developed northeast, traditionally a PT stronghold. Others are disenchanted with Brazil's stagnant economy, in which almost 13 million people are out of work, and a deteriorating security situation which reached a peak a year ago, when a record almost 64,000 homicides were recorded.
The results from the presidential race told only part of the story.
Still, Brazil is split over the danger to democracy posed by Bolsonaro, a long-time congressman who advocates for torture and police violence, praises the country's 1964-85 military regime and suggested that opponents could only win the race through fraud, although he now vows to respect the electoral process.