Early results show President Hassan Rouhani's moderates and reformists may get to dominate the powerful committee. Partial results also show conservatives appearing to lose ground following Friday's parliamentary vote.
State news agency ISNA said on Saturday that Iran's current leader, along with top ally and former President Akbar Hashemi Rafsanjani, were in front for membership of the Assembly of Experts, an important body that chooses the country's highest authority, the supreme leader.
The 88-member committee is likely to be called on to choose a replacement for the 76-year-old Ayatollah Ali Khamenei, who has been in ill health for some time.
In the capital Tehran, 13 out of the top 16 Assembly of Experts candidates were on a list supported by Rafsanjani, media reports said.
With 1.5 million ballot papers counted out of 3.9 million cast in Tehran, Rafsanjani was in first place with 692,000 votes. Rouhani was just behind with 652,000, ISNA reported.
Parliament vote unclear
Meanwhile, local media said the first results from Friday's parliamentary election showed a split of the 290 seat legislature among conservatives, reformists and independent candidates.
The outcome of the vote is being seen as a de-facto referendum on President Hassan Rouhani, who has steered Iran towards a nuclear deal with world powers and a lifting of sanctions that have hurt the economy.
A political moderate, Rouhani is hoping his alliance with reformists, called The List of Hope, can curtail the anti-Western conservative dominance of parliament, improving his chances of passing social and political reforms.
Early results, published by the semi-official ISNA news agency quoting electoral officials, suggested no one faction would win a majority. But the capital, Tehran, appears to have seen sweeping gains for Rouhani's supporters.
Reformists strong in Tehran
The List of Hope was ahead in all but one of Tehran's 30 seats, with 44 percent of the votes counted.
With 56 constituencies reporting outside Tehran, 19 went to conservatives, nine to pro-Rouhani reformists and 14 to independent candidates.
Fourteen other seats will to go to a second round of voting in April because no candidate won 25 percent of the vote, officials said.
Analysts say the high number of independent winners could suggest a partial shift away from Iran's sharply factional politics towards the middle ground.
Interior Minister Abdolreza Rahmani Fazli told state television early results for Tehran's 30 seats would be announced on Saturday evening.
Conservatives usually perform well in the countryside while young town-dwellers tend to prefer moderate candidates.
Around 60 percent of voters cast ballots - 33 million out of 55 million eligible voters - the interior ministry said of Friday's election. Polling stations were kept open until almost midnight in many areas on Friday to allow millions of latecomers to participate.
A total of 4,844 candidates, about 10 percent of whom are women, stood in the parliamentary election. Just a fifth of those vying for the Assembly of Experts were religious clerics.
Final results of both the parliamentary and Assembly of Experts polls must be confirmed by the conservative-dominated Guardian Council, who is charged with monitoring the vote. The results are not expected for several days.
mm/jlw (AFP, Reuters)