Brazilian presidential candidate Flavio Bolsonaro during the presidential debate at the TV Band studios in Sao Paulo, Brazil, on Oct. 18. | BLOOMBERG

Two brothers from Brazil’s richest family have emerged as opponents of right-leaning presidential candidate Flavio Bolsonaro ahead of Sunday’s closely fought runoff election.

Joao and Walter Moreira Salles — scions of the Itau Unibanco Holding fortune with a combined net worth of $17.6 billion, according to the Bloomberg Billionaires Index — are major donors to progressive and left-leaning congressional candidates and have created journalism and films that are critical of the conservative positions held by Bolsonaro, the son of former President Jair Bolsonaro.…