Who is Mojtaba Khamenei, frontrunner to be Iran's supreme leader?

Mojtaba Khamenei is emerging as the leading candidate to become Iran's next supreme leader. He has cultivated strong ties with the Revolutionary Guards and the clerical establishment. The Assembly of Experts is expected to announce its decision soon. Mojtaba faces challenges from US sanctions and potential domestic unrest. His rise follows the death of Ebrahim Raisi.