HAVANA, Cuba (CNN) -- Cuba's National Assembly convened Sunday to choose a head of state -- and for the first time since the 1950s, it won't be longtime leader Fidel Castro.

However, Sunday's election will likely hold no surprises. Raul Castro, 76, Fidel Castro's younger brother, is expected to be named as the country's president.

The 614 members of the Cuban parliament are expected also to choose the country's vice president, assembly secretary and 31 members of the Council of State, which acts on the assembly's behalf when parliament is not in session.

Castro, 81, announced his resignation as president earlier this week, citing in a letter published on the online version of the newspaper Granma his "critical health condition."

"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 letter said.

If chosen as Cuba's president, Raul Castro's role will not be a new one. The former defense minister became Cuba's acting president in 2006, when Fidel Castro underwent intestinal surgery and transferred most of his powers to his brother.

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

As the architect of the Cuban army and its leader for 50 years, Raul Castro has the military firmly behind him. But as Cuba's acting president, he has kept a fairly low profile.

Raul Castro helped his brother plan the 1950s uprising that brought about the Cuban revolution, put Fidel Castro in power and gave birth to the first communist nation in the Western Hemisphere.

The elder Castro, in his first communication since announcing his retirement, lashed out in a Friday newspaper column at President Bush, saying Bush's idea of change for Cuba amounts to annexation of the island nation. E-mail to a friend

CNN's Morgan Neill contributed to this report.

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