Constitutions, like diamonds, are supposed to last. But that is not the view of Nicolás Maduro, a former bus driver chosen by a dying Chávez to replace him as president in 2013. He has ordered a new constituent assembly, to be chosen on July 30th. Everything about the process is different from 1999. In violation of Chávez’s constitution, it has been called by presidential decree rather than by referendum.

Mr Maduro says its purpose is to defeat the opposition’s “fascism”. Yet it will be chosen under a system that might have been devised by Mussolini. Each of the 340 municipalities will elect one assembly member, regardless of size (only state capitals will get two), meaning the opposition-supporting cities are under-represented. A further 181 members will be chosen from communal and occupational groups controlled by the regime.

Mr Maduro wants the assembly because he can no longer stay in power democratically. Low oil prices and mismanagement have exacted a heavy toll. Food and medicines are scarce; diseases long curbed, such as diphtheria and malaria, are killing once more. The opposition won a big majority in a legislative election in 2015. Since then Mr Maduro has ruled by decree and through the puppet supreme court. In almost daily opposition protests since April, 75 people have been killed, many shot by the National Guard or pro-regime armed gangs.

Mr Maduro’s lurch to dictatorship has opened cracks in his political base. Luisa Ortega, the attorney-general and long a chavista, has become an outspoken critic. The constituent assembly will “complete the definitive dismantling of democracy”, she told a Peruvian newspaper this week. Its apparent purpose is to turn Venezuela into a dictatorship along Cuban lines. Already Mr Maduro has instituted a Cuban-style rationing system with food parcels delivered by the armed forces. The assembly, officials say, will assume sovereign power—and sack Ms Ortega.

A last opportunity to apply diplomatic pressure failed last month at a meeting of foreign ministers of the Organisation of American States, held in Cancún. The Mexican hosts thought they had more than the 23 votes needed (out of 34) to condemn Venezuela. They got only 20, as Mr Maduro’s diplomats won over wavering Caribbean mini-states with threats to cut off cheap oil. The outcome, says a Latin American diplomat, depended on how much pressure the United States was prepared to put on the Caribbean. Not enough: Rex Tillerson, the secretary of state, stayed away to deal with Qatar. Though Venezuela is more isolated than ever in its region, Mr Maduro could claim a kind of victory.

Even had the motion passed, it might have changed little. The only potential obstacles to Mr Maduro’s gambit are on his own side. Many chavistas oppose the constituent assembly. “Democratic chavismo is significant in terms of popular sentiment,” says David Smilde, a Venezuela specialist at Tulane University. “But it’s completely disorganised.” Although there have been intermittent protests in chavista areas of Caracas, usually over food shortages, the opposition has failed to link up with dissidents from the regime in a truly national protest movement.

The armed forces, which sustain Mr Maduro in power, have wavered but not bent—so far, at least. Several retired generals who were close to Chávez have criticised the idea of a new assembly. At least 14 junior officers have been arrested since the protests began. On June 20th the president stripped the defence minister, General Vladimiro Padrino, of the powerful post of the operational commander of the armed forces. To some analysts, this looked like an expression of mistrust.

Tension is rising. On June 27th a police officer in a helicopter buzzed the supreme court and interior ministry. A pro-government mob attacked the parliament, and large-scale looting took place in Maracay, west of Caracas.

Mr Maduro and his circle lack the aura of heroism that originally surrounded Fidel Castro. “If chavista Venezuela was a caricature of the Cuban revolution, Maduro is a caricature of the caricature,” says the Latin American diplomat. There is no revolution in Venezuela, just squalid abuse of power. More blood may be spilled before this tragedy ends.