Iran's Assembly of Experts has elected a well-known hardliner in its rank to head the council of clerics responsible for selecting the successor of Supreme Leader Ayatollah Khamenei.

A majority of the 88-member council voted on Tuesday in favour of Ahmad Jannati, keeping the council in the hands of ultra-conservatives, while countering the gains by reformists and moderates during the elections in February.

The 89-year-old cleric, from the southern city of Esfahan, also heads the Guardian Council, which is responsible for overseeing the legislation passed by the country's parliament, and approving candidates for various elections.

He is the father of Ali Jannati, President Hassan Rouhani's culture minister.

Council members, who are elected every eight years, oversee the work of Iran's supreme leader and will eventually pick the successor of Khamenei.

Before the voting, Khamenei, who has the final say on all matters of state, sent a message urging the clerics to work to protect the country's Islamic and "revolutionary" character.

Ghanbar Naderi, a journalist with the Tehran-based Kayhan International, however, said that despite the election of Jannati, the council has "no choice" but to "pave the way" for improved relations with the West.

"The current assembly would be flogging a dead horse if they are still under the illusion that they can elect a very hardline and conservative leadership that is going to stop Iran's interaction with the international community," Naderi told Al Jazeera.

He said the election in February points to an "overwhelming" support for moderation in the country.

Before his election, Jannati also ran but lost the Assembly of Experts chairmanship to former president Akbar Hashemi Rafsanjani in 2007.

Reports on Tuesday said that Rafsanjani had failed to muster enough votes to mount a serious challenge and instead fielded Ebrahim Amini, a 92-year-old moderate figure. The other candidate was former Chief Justice Mahmoud Hashemi Shahroudi.

Ariane Tabatabai, an Iran expert and professor at Georgetown University, said that because of the "internal nomination" process, the position of Assembly of Expert speaker goes to "more conservative figures".

Despite Jannati's victory, she said, the moderates are still "doing pretty well in general" in Iranian politics.

"How this will evolve if Iran doesn't get what it bargained for with the deal is a different story," she told Al Jazeera, referring to the nuclear agreement the Rouhani administration signed with world powers last July.

"That actually is a bigger concern for the moderates than this development."