Senator Flavio Bolsonaro took an early lead as Brazil counted votes Sunday in a closely contested presidential election against incumbent Luiz Inacio Lula da Silva, following a campaign shaped by corruption allegations, economic concerns and accusations of foreign interference.
With about 32% of votes reported, Bolsonaro had 50.74% against Lula's 41.14%, although southern states favorable to Bolsonaro were reporting faster than Lula's northeastern strongholds.
If no candidate receives more than 50% of valid votes, the top two contenders will advance to an Oct. 25 runoff.
Bolsonaro, the 45-year-old son of former President Jair Bolsonaro, is seeking to return his father's right-wing movement to power, while Lula, 80, is pursuing a fourth presidential term.
Polls before voting indicated Lula would likely lead the first round without securing an outright victory, while surveys showed the two frontrunners roughly even in a potential runoff.
Bolsonaro said before the count that he believed opposition to Lula could produce enough support for a first-round victory.
Lula, meanwhile, expressed confidence in his own prospects and emphasized Brazilian sovereignty amid concerns about international influence.
Electoral court chief Kassio Nunes Marques said voting was proceeding normally and authorities had identified no concrete indication of international interference.
The Organization of American States' observation mission also reported that voting was proceeding smoothly under adequate safety conditions.
The election comes amid concerns over living costs, household debt, crime, sluggish growth and Brazil's public finances.
Lula has expanded welfare measures and proposed additional debt relief, while Bolsonaro has emphasized cost-of-living pressures, stronger action against criminal groups and improved relations with the Trump administration.
The campaign was also overshadowed by the Banco Master scandal, which has touched figures across Brazil's political establishment.
Bolsonaro is being investigated for alleged money laundering connected to the case and has denied wrongdoing.
Voters were also choosing all 513 members of the lower house, 54 of Brazil's 81 senators, state legislators and 27 governors, giving Sunday's election consequences extending well beyond the presidency.