MOSCOW — The oldest daughter of Kazakhstan’s longstanding, autocratic president was elected Parliament speaker on Wednesday, fueling speculation that she would succeed her father as the country’s ruler after elections next year.

The appointment of Dariga Nazarbayeva came a day after her father, Nursultan Nazarbayev, who had led the oil-rich Central Asian nation since 1989, when it was still part of the Soviet Union, made the surprising announcement that he was stepping down as president.

Mr. Nazarbayev, 78, retained significant power, however, as head of the Security Council and the ruling party. It remained unclear whether someone from his close circle of political advisers or from his family will emerge to run the opaque system.

“They have opened an era of uncertainty,” said Marlene Laruelle, the director of the Central Asia Program at George Washington University in Washington.