Chavez says he is merely carrying out his campaign promise to shake up the country’s corrupt political elite. Since his left-leaning government took power in February, he has led the effort to reform the country’s 1961 Constitution and clean house. But skeptics–from opposition politicians to American diplomats–fear he is going too far. “We are standing before a dictatorship that is supported in the National Constitutional Assembly,’’ said Timeteo Zambrano, secretary-general of the main opposition party, Democratic Action. In Washington, meanwhile, U.S. officials say things are not hopeless–yet. But they admit they are “deeply concerned” that an assault on democracy in Caracas could threaten political stability throughout Latin America.