Havana blogger Yoani Sanchez, visiting in Brazil, welcomed Diaz-Canel’s promotion but said it was “deplorable” that her joy was caused “not by the politics of a candidate but by his age.”

In another key change, the National Assembly selected Esteban Lazo Hernandez, 69, an orthodox ideologue and Cuba’s top black official, to replace Ricardo Alarcon, a veteran foreign affairs expert who was president of the Assembly for the past two decades.

The selection of Lazo, a member of the Political Bureau in charge of ideology, “confirms the cautious focus on possible changes in the political system,” said Arturo Lopez Levy, a Cuban analyst now at the University of Denver.

Alarcon, 75 and a former ambassador to the United Nations, was not a candidate for the assembly. He told friends he wanted to retire, but rumors of his departure started after police arrested his top aide and the aide’s wife last summer on suspicion of spying and corruption.

During his speech, Castro also declared that the reforms he has launched to rescue the economy, in crisis since the collapse of the Soviet Union and its subsidies, will continue but warned again that the shift toward more private economic activity has its limits.

Castro said he would not accept “shock therapies” — a phrase often used to describe post-communist Europe’s rapid shift toward capitalism — although he added that Cuba will become “less egalitarian, but more just.”

“I was not chosen to be president to restore capitalism to Cuba,” Castro declared. “I was elected to defend, maintain and continue to perfect socialism, not destroy it.”