TEHRAN — An Iranian council that would have the authority to select a new supreme leader elected an 89-year-old hard-liner as its chairman on Tuesday, Iranian state news media reported.

The council, the Assembly of Experts, holds an increasingly important role in light of concerns about the health of the supreme leader, Ayatollah Ali Khamenei, who received treatment for prostate cancer in 2014.

“We should act in such a way that both God and the leader are satisfied with us,” the new chairman, Ayatollah Ahmad Jannati, told the semiofficial Fars News Agency after his election.

The selection of Ayatollah Jannati, who won a majority of the 86 votes, suggested that seniority was a higher priority than the preference of voters. During parliamentary elections in February, Ayatollah Jannati managed to secure the last of 16 seats in the Tehran constituency.