Why does Iran's president have less power than the supreme leader?

Iran’s political system is a theocracy that blends democratic elements with clerical oversight, resulting in a structure where the supreme leader (rahbar) holds ultimate authority over the president.12

While the president is directly elected and manages the day-to-day administration of the government, their power is significantly constrained by the supreme leader, who serves as the head of state and commands influence over virtually all government functions. The supreme leader’s dominance is maintained through several mechanisms:134

• Clerical Oversight: The Council of Guardians, which vets all candidates for public office and reviews legislation, is heavily influenced by the supreme leader, who appoints half of its members.52
• Control of Key Institutions: The supreme leader appoints the chief justice and members of the Expediency Council, which mediates disputes between the parliament and the Council of Guardians.2
• Military Authority: The Islamic Revolutionary Guard Corps (IRGC) answers directly to the supreme leader, rather than the president.2
• Policy Direction: The supreme leader determines the country's overall political direction and oversees the implementation of government policies.4

Ultimately, this concentration of power ensures that the supreme leader maintains control over both the electoral process and national policy-making.14