The NEWSWEEK 50: Iran's Ayatollah Ali Khamenei

Western policymakers would do well to remember Khamenei's title: Supreme Leader. In the Islamic Republic of Iran, presidents come and go. The intemperate, Israel-baiting Mahmoud Ahmadinejad will be lucky if he manages to win a second term in 2009. It is Khamenei, as the authoritative communicator of God's will, who will decide how Iran chooses to exercise its newfound clout in the region. Will he push ahead with Tehran's nuclear program and move from bleeding the United States in Iraq to pricking it in Afghanistan? Perhaps. But it's also true that he's the only Iranian figure with the authority to forge a new relationship with America. No one is more key to Mideast stability.