Its exponents claim that a prolonged emission of white smoke on the first day of balloting at the conclave indicated the election of Siri, but that threats applied from outside the conclave caused his election to be reversed, allowing Pope John XXIII to be elected two days later. The source of the threats has been identified variously as Freemasons and agents of the Soviet Union. Adherents of the Siri thesis say that the election of John XXIII was invalid. They regard him and his successors as imposters and antipopes.