Brazilians are voting Sunday in a presidential runoff that pits leftist incumbent Luiz Incio Lula da Silva against Sen. Flvio Bolsonaro, a far-right ally of U.S. President Donald Trump.

Bolsonaro, the son of imprisoned former President Jair Bolsonaro, bested Lula by more than 2. 2 million votes in the first round of the election earlier this month.

More than 33 million of the nearly 160 million registered voters did not turn out.