Prominent leaders of Brazil’s opposition have called for president Jair Bolsonaro to be immediately removed from office to prevent his “coup-mongering, authoritarian delusions” becoming a reality. “We cannot be bystanders to this barbarism,” congressman Marcelo Freixo said on Wednesday as parliamentarians demanded Bolsonaro’s impeachment for what they called his illegal attempt to co-opt the armed forces. Bolsonaro’s decision to sack Brazil’s defence minister Gen Fernando Azevedo e Silva – and the subsequent departures of the heads of all three branches of the military – has sent political shockwaves through the world’s fourth-largest democracy. “There is an attempt here by the president to arrange a coup – it is under way already – and that is why we are reacting,” claimed Alessandro Molon, the leader of the opposition in the lower house, as the impeachment request was presented to congress. Gen Azevedo e Silva was relieved of his duties on Monday, with members of the military establishment pushing the idea that he was sacked for resisting Bolsonaro’s plans for a “coup-mongering adventure”. Hours later, on Tuesday morning, the heads of the army, air force and navy were reportedly dismissed during an ill-tempered meeting after Bolsonaro had discovered they were poised to resign in protest. The sudden and dramatic fissure between Brazil’s far-right president and the military men who helped bring him to power in 2018 has yet to be fully explained. Some observers suspect senior members of the armed forces had decided to ditch Bolsonaro’s crisis-stricken administration – partly out of frustration at his calamitous handling of an uncontrolled coronavirus outbreak that has killed nearly 320,000 Brazilians. Others believe military chiefs may genuinely have been trying to protect Brazilian democracy after Bolsonaro, a former army captain known for his admiration of dictators, attempted some kind of authoritarian move such as a self-coup, by which a democratically elected leader takes on dictatorial powers. João Roberto Martins Filho, a leading military expert, said at least eight different explanations for the rupture were circulating, and it was unclear which was true. “We don’t even know yet what Bolsonaro proposed. He’s crazy enough to propose these kinds of things but we just don’t know and it will be hard to find out,” Martins Filho said, adding that he was unconvinced by the ousted military commanders’s efforts to position themselves as defenders of democracy. “They elected Bolsonaro, they supported Bolsonaro, they filled Bolsonaro’s entire government – and now they want to come out of this as democrats,” he said. “If they were really in favour of the constitution they would go back to their barracks and take care of national security, as they do in European countries.” Whatever happened, few doubt the week’s drama represents a pivotal and potentially dangerous moment in the modern history of a country that only emerged from two decades of dictatorship in 1985. “This is a major moment for Brazilian democracy,” said Brian Winter, a Brazil specialist and the editor-in-chief of Americas Quarterly. Winter said he suspected Bolsonaro had been trying to fill the military top brass with more amenable figures who might help shield him from impeachment or come to his rescue if he failed in his bid to win re-election next year. Bolsonaro’s fears over his ability to secure a second term appear to have intensified in recent months, with polls showing his handling of Covid has dented support and the unexpected re-emergence of his political nemesis Luiz Inácio Lula da Silva. Lula, a charismatic former union leader who led Brazil from 2003 until 2011, was prevented from challenging Bolsonaro in the 2018 election because of a corruption conviction that was recently quashed. But the 75-year-old now looks likely to run against Bolsonaro in the 2022 and has spent recent weeks excoriating his rival’s “moronic” handling of coronavirus. “Bolsonaro is worried about impeachment and he’s also worried about Lula,” Winter said. “I don’t think you will ever see Jair Bolsonaro hand the presidential sash to Luiz Inácio Lula da Silva” Arlindo Chinaglia, an opposition politician who is also backing the impeachment request – one of more than 60 submitted against Bolsonaro – admitted the president’s removal would only be possible if society mobilized against his “authoritarian misdemeanors”. In the wake of this week’s political crisis he urged citizens who cherished democracy – including those who voted Bolsonaro into power – to wake up to the threat. “We have a president who is trying to pressure the armed forces into serving his coup-mongering, authoritarian delusions,” Chinaglia said, remembering the military coup that plunged Brazil into dictatorship exactly 57 years ago, on 1 April 1964. “Showing excessive tolerance to those who attack democracy day after day has never been the correct way to behave,” he added.