Iranians will return to the polls for a run-off presidential vote on July 5, after none of the candidates scored a majority in the first round.

The election is to replace president Ebrahim Raisi, who was killed in a helicopter crash last month.

Reformist Masoud Pezeshkian holds a slim lead over conservative Saeed Jalili. Turnout sank to a record low of only 40 percent.

But with Supreme Leader Ali Khamenei holding ultimate authority, even if Pezeshkian were to triumph in the second round, many experts say his ability to bring in real reforms would be severely limited.

00:00 Iranian presidential election headed to run-off
00:42 Danny Citrinowicz from the Israeli Institute for Security Studies
04:16 Roya Boroumand, the Abdorrahman Boroumand Center for Human Rights in Iran