The Vatican
Office of the Secretary of State
Handles all political and diplomatic responsibilities
Secretariat of State, recognized as the oldest and most significant department of the Roman Curia. This Secretariat handles all political and diplomatic responsibilities for the Holy See and Vatican City.
The Cardinal Secretary is appointed by the Pope and acts as one of his chief advisors. As a high-ranking position within the Roman Catholic Church, the Secretary must be a cardinal. If the position is vacant, a non-cardinal may temporarily serve as Pro-tem Secretary of State, exercising the powers of the Secretary of State until a suitable replacement is found or the Pro-Secretary is elevated to cardinal status in a subsequent consistory.
The Cardinal Secretary's tenure concludes when the Pope who appointed him either passes away or leaves office. During the sede vacante period, the former Secretary participates as a member of a commission along with the Camerlengo of the Holy Roman Church and the former President of the Pontifical Commission for Vatican City State. This commission assumes certain functions of the head of state of Vatican City until a new Pope is elected. Once a new Pope is chosen, the former Secretary's role in the commission also ends, though he may be reappointed as Secretary of State..1