Flávio Bolsonaro posted a letter from the US declaring himself "the true president-elect of Brazil," claiming electoral fraud had deprived him of victory, without providing evidence

President Luiz Inácio Lula da Silva faces Senator Flávio Bolsonaro in a closely contested election. A Datafolha survey of 2,506 people, conducted 29 September–1 October across Brazil, put a hypothetical run-off at 48% to 45%; Reuters described the result as a statistical tie within the poll's two-point margin of error. The first round on 4 October produced a run-off between Lula and Flávio Bolsonaro.

Flávio Bolsonaro, who lost the 25 October runoff to Lula, declared himself the rightful president-elect in an open letter shared with journalists on 28 October. The letter alleges electoral fraud, citing a two-hour voting extension and a rise of over 10 million votes for Lula between rounds, and says he will lead the opposition from the United States; Reuters reports he provided no evidence. Brazil's electoral court declared Lula the winner by 4,430,191 votes, and fewer than 35,000 votes were cast during the extension.