HAVANA, Cuba (CNN) -- Fidel Castro's nearly five decades of rule ended Sunday when Cuba's National Assembly chose his younger brother Raul to be the country's new president.

The lawmakers' selection, which had been widely expected, came five days after Fidel Castro, 81, announced his resignation in a letter published in the state-run newspaper Granma.

In his address to the National Assembly, the 76-year-old Raul Castro proposed that "we consult Fidel" on important decisions. The 614 members of the legislative body passed that motion unanimously.

The lawmakers also announced that Jose Ramon Machado, a man of Raul Castro's generation, had been elected first vice president of the Council of State, despite the expectation of some that the post would go to someone younger.

The Council of State acts on behalf of the Assembly -- which meets only twice a year -- when it is not in session. Watch how Fidel Castro will still play a role in Cuba »

Juan Almeida Bosque, Abelardo Colomi Ibarra, Carlos Lage Davila, Esteban Lazo Hernandez and Julio Casas Regueiro were elected as the Council's other vice presidents, according to Granma.

Fidel Castro was not present at the National Assembly meeting.

In his letter of resignation published in the newspaper, he cited his "critical health condition" and said, "It would be a betrayal to my conscience to accept a responsibility requiring more mobility and dedication than I am physically able to offer."

The elder Castro underwent intestinal surgery in 2006, when he transferred some powers to Raul, the country's longtime defense minister.

In his first communication since announcing the announcement, Fidel Castro lashed out Friday at U.S. President Bush in a newspaper column, saying Bush's idea of change for Cuba would amount to annexation of the island nation.

He said that, after his announcement, "I slept better than ever ... My conscience was clear and I promised myself a vacation."

Raul Castro, who is shorter, less imposing and less charismatic than his brother, was the architect of the Cuban army and its leader for almost 50 years. As Cuba's acting president, he has kept a low profile.

About six months ago, he began what he called a "national debate" on the problems of the country, acknowledging high unemployment and other economic concerns.

"Is there going to be a transition here toward something?" Raul Castro once told reporters asking about post-Fidel Cuba. "Yes, toward a better form of socialism and -- here's something you'll like -- toward a more democratic society."

However, he has said that only the Communist Party can guarantee continuity and, in his address Sunday to the National Assembly, he called the Party the "the guarantee of the Cuban nation."

Raul Castro helped his brother plan the uprising that brought about the Cuban revolution, put Fidel Castro in power in 1959 and gave birth to the Western Hemisphere's first Communist power.

The brothers were born in Biran, Cuba, sons of a Spanish immigrant -- a rich landowner -- and a housemaid whom he eventually married.

During the early years of the revolution, the younger Castro earned a reputation for being ruthless with his enemies. Grainy black-and-white video shows him making impassioned speeches in the early days of the revolution. Even before his brother announced his retirement, Raul Castro said Fidel would be a hard act to follow.

Fidel Castro's daughter, Alina Fernandez, who lives in Florida, told CNN that Sunday's events were unlikely to significantly affect the country.

She has long opposed her father's regime.

"I think that the government will remain mostly the same, but I think they are going to bring on different faces that they need," she said. E-mail to a friend

CNN's Shasta Darlington contributed to this report.

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