Several thousand Brazilians marched Saturday in support of far-right president Jair Bolsonaro, ignoring a surging pandemic even as government opponents took their own protests online.
There were rallies in Brasilia, Sao Paulo and Rio de Janeiro, with many demonstrators wearing the yellow, blue and green of the country's flag.
Brazil, with more than 403,000 Covid-19 deaths, is second only to the United States in that grim category, and Bolsonaro faces widespread criticism for not taking the pandemic more seriously.
Two weeks ago, the president said he was waiting for "a sign from the people" before "taking measures" to revoke restrictions imposed by mayors or governors to contain the spread of the virus.
More recently, he told a television interviewer that the army "could take to the street one day, to ensure respect for the Constitution (and for) freedom to come and go."
In Rio on Saturday, several hundred protesters seemed to respond to his call. Rallying along celebrated Copacabana beach, they waved banners demanding a "military intervention" to bolster Bolsonaro's powers.
A slogan widely seen at the various rallies was "Autoriso Bolsonaro" ("I authorize Bolsonaro") to send in the army.
In Brasilia, several thousand people assembled on the Esplanade of Ministries as Bolsonaro briefly passed overhead in a helicopter.
One of his sons, the deputy Eduardo Bolsonaro, waded into the crowd, his mask worn down around his chin, taking selfies with supporters, their faces also uncovered.
"It's a critical moment and Bolsonaro needs the people's support," Edvaldo de Paulo, a sixtyish demonstrator, told AFP in Brasilia.
"We have to clean house in Brasilia to let the president govern," said Elenir Ritonni, a 63-year-old retiree who joined several hundred demonstrators in Sao Paulo.
Bolsonaro spoke via videoconference during a farm event.
"It used to be that on May Day red flags would wave, as if we were a socialist country. I am happy to see green and yellow flags all over the country, with people who are truly working," he said.
Few anti-Bolsonaro protests were planned for Saturday, but key opposition leaders, on the right and the left, were taking part in a trade union-sponsored event on social media critical of Bolsonaro.
Among them were former president Luiz Inacio Lula da Silva (2003-2010), who is expected to challenge Bolsonaro in next year's elections, and his center-right predecessor, Fernando Henrique Cardoso (1995-2002).
"This is a sad May Day for the workers of our country, a day of mourning for the 400,000 lives lost to Covid-19, many of them because the government of Bolsonaro refused to buy the vaccines that were being offered," Lula said.
On Tuesday, a Senate commission of inquiry was established to examine the government's handling of the health crisis, with many experts saying it has been incompetent and irresponsible.