The head of President Luiz Inacio Lula da Silva's Workers Party resigned on Friday, amid a purge of party leaders in a political scandal that has battered the incumbent's re-election chances.
Ricardo Berzoini, who had earlier stepped down as Silva's campaign manager but stayed on as party president, said he was resigning as president of the Workers Party to maintain its "unity and cohesion."
Analysts say the corruption scandal cost Silva key support ahead of the first round of voting last Sunday, when he failed to win a 50 percent plus one vote majority and was forced to an Oct. 29 runoff against former Sao Paulo state Governor Geraldo Alckmin.
On Friday evening, officials also said the center-left party would expel all members involved in the scandal, in which highly placed leaders are accused of trying to purchase information that apparently incriminated a rival politician in a separate scandal.
It was unclear how many members were involved in the purge, but at least seven campaign officials have been named in recent days in the alleged plot.
Berzoini had come under pressure to step down to distance Silva from the corruption allegations ahead of the runoff vote. He said on Friday he supported an investigation into the allegations and denied any involvement, though one of his subordinates has been implicated.
"I reaffirm that I never promoted or agreed with any form of illegality or irregularity in matters under my responsibility," Berzoini said, adding he could return as party president after the investigation was complete.
Workers Party officials said Berzoini would be replaced by Marco Aurelio Garcia, a former adviser and current campaign manager for Silva.
Alexandre Barros, a political analyst with Early Warning consultants in Brasilia, said the move should help Silva's campaign.
"Everybody allegedly involved in the scandal was a liability for Lula," Barros said, using Silva's popular nickname. "It doesn't matter if they are guilty or not. It only matters that people think they are," he added.
A poll released on Friday showed Silva, Brazil's first working-class president, leading in the runoff, with 54 percent of the valid votes compared to Alckmin's 46 percent.
According to a federal police investigation, former Berzoini aide Oswaldo Bargas attempted to pay US$780,000 for a dossier with incriminating information about Jose Serra, a member of Alckmin's Social Democratic Party who lost the presidential election to Silva in 2002.