FACTBOX: Possible changes in Cuba's leadership

HAVANA (Reuters) - Ailing Cuban leader Fidel Castro, who has not appeared in public for more than 18 months, could retire from politics this month after almost 50 years at Cuba's helm.

The following are possible scenarios when the National Assembly legislature meets on February 24 to ratify the country's top leadership posts:

CASTRO STEPS DOWN

* Fidel Castro declines the presidency in person or in a written statement to the assembly, citing his illness. He could also announce prior to the meeting that he is too weak to be eligible for the presidency. Either would be tantamount to his political retirement, ending an era that he has dominated since seizing power in a 1959 revolution.

* If Castro steps down, he is expected to formally hand over power to his brother Raul Castro, 76, who has run the country "temporarily" since Castro underwent emergency intestinal surgery in July 2006.

* The baton could be passed 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.

NO CHANGE

* Fidel Castro is unanimously proclaimed head of state, but again cedes power temporarily to his brother Raul Castro, as he did on July 31, 2006.

CASTRO PLANS RETURN

* Fidel Castro is declared head of state and announces that he is healthy enough to resume day-to-day control of the country. Most analysts think this is unlikely.

NEW ROLES

* Fidel Castro could remain on the 31-member Council of State, Cuba's top executive body, but not have a leadership role on it, while continuing to wield power as first secretary of the ruling Communist Party.

* 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 either of the Castro brothers in the figurehead role, and Raul Castro or Lage in a prime ministerial role.

(Reporting by Anthony Boadle; Editing by Kieran Murray)