Nearly a half century of rule by Fidel Castro was ending Sunday as Cuban lawmakers chose his replacement -- widely expected to be his younger brother Raul.

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The transition was not likely to bring a major shift in policies of the communist government that have put it at odds with the United States. But many Cubans were hoping it would open the door to modest economic reforms and improvement in their daily lives.

The parliament was choosing a new 31-member ruling body known as the Council of State to lead the country. The council's president serves as the head of state and government.

In his final essay as president, the ailing, 81-year-old Castro wrote that preparations for the parliament meeting "left me exhausted," and he said he did not regret his decision to step down.

"I slept better than ever," he wrote in the commentary published on Friday. "My conscience was clear and I promised myself a vacation."

The U.S. has said the change from one Castro to another would not be significant, calling it a "transfer of authority and power from dictator to dictator light."

Secretary of State Condoleezza Rice said Sunday Cubans have a right "to choose their leaders in democratic elections" and urged the government "to begin a process of peaceful, democratic change by releasing all political prisoners, respecting human rights, and creating a clear pathway towards free and fair elections."

Her statement, issued shortly before parliament met, called the developments a "significant moment in Cuba's history."

With Sunday's vote, Castro's 49 years as head of the communist state in America's backyard will come to an end. He retains his post as a lawmaker and as head of the Communist Party. But his power in government has eroded since July 31, 2006, when he announced he had undergone emergency intestinal surgery and was provisionally ceding his powers to 76-year-old Raul.

The younger Castro has headed Cuba's caretaker government in the 19 months since then, and Fidel Castro has not appeared in public.

Castro was among the 614 members of parliament elected on Jan. 20 but his seat was empty at Sunday's gathering. As the names of the new National Assembly's members were read aloud, mention of the absent Castro drew a standing ovation. Parliament gave another standing ovation to Raul.

If the first round of voting Sunday, National Assembly President Ricardo Alarcon was nominated for re-election to his post, effectively removing him as a dark horse candidate for the presidency of the ruling council.

Lawmakers then began filling out paper ballots to be filed secretly on his post and other parliament positions.

Fidel Castro's ballot with his votes for governing Council of State members, including his replacement, was delivered to parliament.