The official shortlist of candidates that will be bidding to succeed Iranian President Mahmud Ahmadinejad in the June 14 election is set to be announced this week.

More than 600 men and women registered their names to become presidential candidates during a five-day registration period that ended on May 11. The task of vetting the nominees and determining a shortlist of approved candidates falls on the Guardians Council, a constitutional watchdog.

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Under Iran’s election laws, the powerful council must submit its list to the Interior Ministry by May 21. The ministry, which organizes the poll, then has until May 23 to declare the final names. The handful of candidates who pass the council’s screening will then have three weeks to campaign.

The unelected Guardians Council is made up of 12 members, six of whom are appointed directly by Supreme Leader Ayatollah Ali Khamenei. The other six are appointed by the judiciary, which itself is selected by the supreme leader.

The eligibility of the candidates is based on tangible criteria such as education qualifications, political experience, and age. Candidates must be at least 18 years old, but an upper age limit has not been set.

But there are also more controversial and intangible criteria, such as a candidate’s devotion to Shi’ite Islam, the state religion, and their belief in the principles of the Islamic republic.

Supreme Leader Ayatollah Ali Khamenei

Iran’s election laws grant the council sweeping powers known as "arbitrary supervision," which mean it can subjectively disqualify candidates even if they satisfy the criteria.

Scott Lucas, an Iran specialist at Birmingham University in Britain and editor of the EA World View website, says the council’s decision, therefore, is based more on politics than the credentials of the candidates.

"The official answer is that it's based on the qualifications of the candidates and their suitability under an Islamic system," Lucas says. "But what we have previously seen is candidates saying, 'Look, I’m suitable to run,' but their critics saying they're not suitable to run. So, with the council’s decision, there’s no published record of how they reach decisions. They simply declare that these are the people who can go forward."

Patrick Clawson, director of research at the Washington Institute for Near East Studies, says Khamenei's influence over the council will almost certainly mean the supreme leader will have ultimate say on who is on the shortlist of presidential candidates.

"Well, the supreme leader almost certainly tells the Guardians Council who they should list and who they should not," Clawson says. "He may provide guidance to the council rather than a list of specific names."

In the past, Clawson says, that has meant that the conservative council has shunned many candidates outside the ruling elite -- including reformists, moderates, and women.

The international community has often criticized what it has called Iran’s murky vetting process. The latest to comment was U.S. Undersecretary of State Wendy Sherman, who told U.S. lawmakers on May 15 that the Guardians Council was using "vague criteria" to eliminate potential candidates.

Sherman told the Senate Foreign Relations Committee, “Without a transparent process, it is difficult for us to say whether Iran's elections will be free, fair, or represent the will of the Iranian people.”