A moderate conservative who led Iran's elite Revolutionary Guards said Wednesday that he will become the latest challenger to incumbent Mahmoud Ahmadinejad for the Iranian presidency in June.

Mohsen Rezaei is not seen as a leading challenger but reformists who see a strong opportunity to unseat Ahmadinejad in the June 12 election hope Rezaei may be able to take votes away from the incumbent. Rezaei has opposed Ahmadinejad's handling of the economy and his hard-line foreign policy.

Rezaei led the Revolutionary Guards during the Iran-Iraq war in the eighties and afterward but then retired from the military to enter politics.

The 57-year-old enjoys support in his home base of the oil rich province of Khuzestan in southwestern Iran. He's believed to enjoy support from Iran's powerful former president, Akbar Hashemi Rafsanjani.

Ahmadinejad's advisers have said the president will seek re-election. Under Iranian law, a president can run for two, consecutive 4-year terms.

The leading challenger to Ahmadinejad in the presidential election is Mir Hossein Mousavi, an influential former Iranian prime minister whose intention to run is posing what could be a serious challenge to Ahmadinejad.

Iran's reformers, who favor improving ties with the West and loosening restrictions at home, see a chance for victory in June. The president has lost popularity even among some conservatives because of his handling of the faltering economy, and some Iranians believe his tough anti-U.S. and anti-Israel rhetoric has worsened Iran's isolation in the world.

But the reformists must also unify their ranks. Besides Mousavi, there is another pro-reform candidate: former parliament speaker Mahdi Karroubi. To increase their chance of unseating Ahmadinejad, reformists need to come up with a single candidate because their votes will split if they don't.

Karroubi has repeatedly said he won't drop out regardless of who else is running.

Rezaei has said he would seek a government of "national coalition" if elected.