Ayatollah Mohammad Taghi Mesbah Yazdi is a hardline Iranian Twelver Shi'i cleric and politician who is widely seen as Iranian President Mahmoud Ahmadinejad's spiritual advisor. He is also a member of Iran's Assembly of Experts, the body responsible for choosing the Supreme Leader, where he heads a minority ultraconservative faction.He has been called the most conservative and the most powerful and influential, clerical oligarch in Iran's leading center of religious learning, the city of Qom.