FACTBOX: Leadership changes in Cuba

(Reuters) - Cuba's acting President Raul Castro is expected to be confirmed as Cuba's new head of state by the National Assembly on Sunday, following his ailing brother Fidel Castro's retirement.

The following are possible leadership scenarios when the assembly ratifies the 31-member Council of State, Cuba's top executive body:

RAUL CASTRO

* Raul Castro, 76, the world's longest-serving defense minister and acting president since his brother fell ill in July 2006, is formally made president and head of state. This includes the prime-ministerial role as cabinet president. No surprises. Raul has run the country for 19 months.

* The baton could, in theory, be passed on directly to a younger leader, such as Vice President Carlos Lage, 56, as the new head of state. Most Cuba watchers doubt such a big change will occur in the leadership vacuum left by Fidel Castro. Raul gives the new government more legitimacy and continuity.

FIDEL CASTRO

* Fidel Castro told Cubans on Tuesday he was no longer well enough to govern and would soldier on in the "battle of ideas" through his writings. But he could still, theoretically, have a seat in the Council of State, as he is a deputy in the National Assembly. This was not considered likely, though, for the revolutionary icon.

* Fidel Castro continues to hold the powerful post of first secretary of the ruling Cuban Communist Party. He is expected to continue to lead the PCC until its next congress at the end of this year or the beginning of 2009. Health permitting, he will remain a key player, and king-maker behind the scenes.

OTHER FIGURES

* Carlos Lage will likely be promoted to First Vice President, Raul Castro's current position, having a more hands-on role in day-to-day governing.

* Cuba could reform its constitution to split the post of head of state (president of the Council of State) and head of government (president of the Council of Ministers), with Lage heading the latter as a virtual prime minister. It is not clear that such an amendment can be completed on Sunday.

* Foreign Minister Felipe Perez Roque, a close Fidel Castro aide and rising star among Cuba's young generation of leaders, could become one of the five second-tier vice presidents.

* One old guard member who could be promoted to vice president is Communications Minister Ramiro Valdes, a hard-line former security chief.

(Reporting by Anthony Boadle in Havana; Editing by Kieran Murray and David Storey)

(For special coverage from Reuters on Castro's retirement, see: here)