Castro, 81, who has not appeared in public since undergoing stomach surgery almost 19 months ago, said he would not seek a new term as president or leader of Cuba's armed forces when the National Assembly meets on Sunday.
"To my dear compatriots, who gave me the immense honor in recent days of electing me a member of parliament ... I communicate to you that I will not aspire to or accept -- I repeat not aspire to or accept -- the positions of president of the Council of State and commander-in-chief," Castro said in a statement published in the Communist Party's Granma newspaper.
His brother Raul takes over:
Cuba's National Assembly, a rubber-stamp legislature, is expected to nominate Castro's brother and designated successor Raul Castro as president. The 76-year-old defense minister has been running the country since emergency intestinal surgery forced his brother to delegate power on July 31, 2006.
Cubans have had time to get used to Raul, so I won't expect a revolt with Castro gone. But without his history, can Raul maintain control of Cuba for long?
And will Hugo Chavez seek to destabilize Raul in order to seize the mantle of revolutionary leader in Latin America? Denied this role in Venezuela, will Chavez try to burnish his credentials by supplanting Cuba as the leading revolutionary country?
Cuban communists may think they've made a smooth transition. Hugo may have other ideas.