Paulo Cid Engineer, 55, who participated in one of those recent motorcycle rallies, said he regarded Mr. Bolsonaro as a fundamentally honest leader who has been unfairly attacked by scientific institutions and by the news media.
“I confess that my indignation turned into emotion,” he said, recalling how he felt at a pro-government rally earlier this month in Rio de Janeiro. “I will be able to tell my children and grandchildren that I took my part in a movement seeking a better country.”
The government has also been shaken by scandals unrelated to the pandemic.
The Estadão newspaper revealed in early May that Mr. Bolsonaro’s administration had steered hundreds of millions of dollars to questionable initiatives and purchases that strengthened the hand of key allied lawmakers. One case involved the government’s purchase of tractors at a 259 percent markup.
Days after the Estadão report, federal police served search warrants at the ministry of the environment as part of an investigation into a suspected scheme to authorize illegal exports of timber from the Amazon.
Amid the drumbeat of bad news, Mr. Bolsonaro has kept a busy travel schedule, focusing on electorally important states in northeast Brazil, where he has highlighted investments in infrastructure and basic services.
The president’s main political rival, former President Luiz Inácio Lula da Silva, has refrained from endorsing street protests. But Mr. da Silva, who recently won court battles in a corruption case, which restored his right to run for elected office, is clearly relishing the prospect of a grass roots face-off against a beleaguered incumbent. Recent public opinion polls show Mr. da Silva narrowly edging Mr. Bolsonaro in next year’s presidential contest.
“When Bolsonaro goes to the streets, he needs thousands of police officers to protect him,” Mr. da Silva wrote on Twitter on Saturday. “Does he think I’m afraid of him? I was born on the streets and spent my whole political life on the streets.”
Ernesto Londoño reported from São Paulo, Brazil, and Flávia Milhorance from Rio de Janeiro.