Thousands of supporters of Brazilian President Luiz Inácio Lula da Silva marched this Sunday in several cities in favor of his reelection and with protest messages against a corruption scandal in which his rival, Flávio Bolsonaro, is under investigation.

The campaign has been shaken by revelations about the relationships of Daniel Vorcaro, owner of Banco Master and imprisoned for using that entity in an alleged fraud, with figures from various political camps, including Senator Flávio Bolsonaro.

Three weeks before the first round of an election anticipated to be close, crowds dressed in the red shirt of Lula's Workers' Party marched in Brasilia and Rio de Janeiro.

In the "cidade maravilhosa," thousands of people responded to the call of the president's campaign to march along Copacabana beach. In Brasilia the attendance was similar, at an event led by First Lady Rosangela 'Janja' da Silva, AFP reporters confirmed.

In Sao Paulo a smaller group demonstrated in the rain.

Authorities did not release figures on attendance at these demonstrations.

The eldest son and political heir of far-right former President Jair Bolsonaro, Flávio "has ties to all the corruption schemes that are in the news today, with Banco Master," Leonardo Mattos, a 37-year-old university professor who will vote for Lula, told AFP in Rio de Janeiro.

Judicial documents released on Friday revealed that police have been investigating Flávio for months on suspicion of corruption and money laundering in the financing of a biopic about his father, titled "Dark Horse."

The candidate met several times with Vorcaro to ask him for money for the production. Before going to prison, the banker contributed about 12 million dollars, according to case documents obtained by AFP.

Flávio Bolsonaro admitted in May to having asked the banker for million-dollar transfers for "Dark Horse," but claims the process was "totally legal."

In Rio, demonstrators raised signs with the faces of both men and the slogan "the far right is rotten and corrupt."

The most recent polls show a technical tie between Lula and Flávio Bolsonaro in a potential second-round vote, which would be held on October 25.