Iranians are choosing Friday between four presidential candidates, but the race is really between incumbent President Hassan Rouhani, 68, a moderate cleric, and his hardline main opponent, Ebrahim Raisi, 56 (pictured). No Iranian president has lost a re-election bid since 1981, but Raisi has put together a coalition of religious conservatives and populist isolationists that makes him a serious contender. He is also seen as the favored candidate of Iran's supreme leader, Ayatollah Ali Khamenei, though Khamenei did not endorse anyone in the race.
The election is expected to have a lasting impact on Iran's relationship with the West, especially with regard to the nuclear deal Rouhani negotiated with the U.S. and other world powers. If Raisi wins, he is expected to scrap the deal, and will also likely become the frontrunner to replace Khamenei, who is 70 and in poor health. In Iran, presidents have real power but it is subject to approval from the ayatollah, who is chosen by a clerical panel. Iran has 56 million eligible voters, and turnout should exceed 70 percent, athorities predict. Polls close at 6 p.m. local time (9:30 a.m. EDT), though Iran typically keeps polls open for several hours past the scheduled cutoff.