Iranian officials have set a deadline for presidential candidates to officially register for the country's June 12 elections.
State television Tuesday reported that the Interior Ministry set May 3 as the beginning of a five-day registration period.
President Mahmoud Ahmedinejad has not formally announced his candidacy but is widely expected to seek another term.
Former President Mohammad Khatami, a reformer, has said he will run, as has fellow reformer, Mehdi Karroubi. In addition, former Prime Minister Mir Hossein Moussavi is expected to enter the race.
During his previous two terms (from 1997 to 2005), Mr. Khatami strove to improve relations with the West. His efforts to relax some religious restrictions on social activity were blocked by Iran's powerful clerics.
Although many of his supporters became disillusioned with his presidency, many reformists believe Mr. Khatami has the best chance of unseating Mr. Ahmadinejad, who is seen as having the backing of Iran's supreme leader, Ayatollah Ali Khamenei.
Mr. Ahmadinejad's domestic critics accuse him of provoking international isolation with vitriolic statements against Israel and the United States. They also blame him for Iran's high inflation, which hovers around 30 percent.
Some information for this report was provided by Reuters.