Former President Luiz Inácio Lula da Silva took the most votes in Sunday’s first round of Brazil’s presidential elections, but President Jair Bolsonaro’s better-than-expected performance means the two will face each other again in a runoff vote at the end of the month.

Mr. da Silva, a standard-bearer of the Latin American left who is widely popular among the poor despite having been jailed on a corruption conviction in 2018, clinched 48.2% of the vote. The tally was just shy of the majority he needed to win outright, with 99.1% of votes counted Sunday night, according to Brazil’s electoral court.