To varying degrees, several of Mr. Bolsonaro’s most prominent allies have already recognized President-elect Luiz Inácio Lula da Silva’s victory, as have the Superior Electoral Court, the heads of both the House and Senate, and several major world leaders.

But Mr. Bolsonaro, more than 12 hours after the result became final, has yet to open his mouth.

Brazil’s electoral system makes the strategy of a U.S.-style “Big Lie” much more difficult....

Voters who swept Luiz Inácio Lula da Silva back into the presidency Sunday fondly recall his last heady two terms in office in the 2000s when commodity prices were soaring, poverty was plunging and Brazil was finally seen as the country of the future.

“The people will eat steak and drink beer again…they will be happy again,” Mr. da Silva told supporters in the campaign that ended with Sunday’s victory over President Jair Bolsonaro, who has yet to concede or comment on the results. 

A day after an inconclusive presidential election, Brazil is now bracing for a frantic four-week campaign ahead of a runoff vote that will pit leftist Luiz Inácio Lula da Silva against Jair Bolsonaro, the far-right incumbent president.

Official returns from Sunday's first round showed da Silva, a former two-term president universally known as Lula, with 48.4% compared to 43.2% for Bolsonaro. The remaining votes went to nine other candidates.

Brazil's presidential election sparked a second round of voting after neither major-party candidate received more than 50% of the votes.

With more than 99% of the vote counted, former president and left-wing candidate Luiz Inacio “Lula” da Silva led incumbent right-wing President Jair Bolsonaro with 48.4% of the vote, according to results released by Brazil’s Electoral Superior Court. Bolsonaro received 43.2% as of Sunday evening.

Former Brazilian President Luiz Inácio Lula da Silva, who governed Brazil between 2003 and 2010, came close to winning his old job back in an outright victory in the country’s presidential election on Sunday, as voters expressed their rejection of incumbent Jair Bolsonaro. However, the former president didn’t obtain quite the margin he had hoped.