João Doria is the governor of São Paulo, Brazil's wealthiest state. He was once an ally of Brazilian President Jair Bolsonaro. But the two men have clashed over how to handle the coronavirus pandemic.
On Tuesday it was announced that 615 people had died of Covid-19 in Brazil in 24 hours - the highest death toll for a single day anywhere in the southern hemisphere.
Doria has imposed a state-wide quarantine to slow the virus; Bolsonaro wants only the most vulnerable to stay at home and is keen for people to return to work.
Bolsonaro has repeatedly downplayed the threat of Covid-19 and, last month, he controversially joined an anti-lockdown rally where he was seen coughing without covering his mouth.
This has put Doria on a collision course with Bolsonaro. "We have two viruses to combat, coronavirus and Bolsonaro virus," Doria told the BBC's South America correspondent Katy Watson.