Neither President Luiz Inácio Lula da Silva nor Flávio Bolsonaro, the son of a former president, won the first round, but Mr. Bolsonaro took more votes.

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Luiz Inácio Lula da Silva, the leftist incumbent, and Flávio Bolsonaro, the right-wing challenger, face off in a race that could define the future of Latin America.

© Victor Moriyama for The New York Times