After Ahmadinejad

Iranian President Mahmoud Ahmadinejad's preferred successor, Esfandiar Rahim Mashai, will not be running in the June 14 election. Neither will former President Akbar Hashemi Rafsanjani. The disqualification of both sends a strong message from Supreme Leader Ayatollah Ali Hosseini Khamenei. Simply put, Khamenei will not tolerate any diminution of his power, and he is determined to avoid the type of friction that has characterized his relationships with previous presidents, particularly Ahmadinejad.

The disqualification of Mashai and Rafsanjani reveals, once again, the schism embedded at the heart of Iran's political structure by the dual executive of Supreme Leader and President. When Khamenei publicly supported Ahmadinejad's controversial reelection in 2009, no one could have predicted the unprecedented tensions that would subsequently emerge between the country's two main authorities.

But supporting Ahmadinejad turned out to be a costly decision for Khamenei -- and for the Islamic Republic. Instead of aligning himself with Khamenei, as expected, Ahmadinejad began to promote a nationalist, anti-clerical agenda, effectively using Khamenei's resources to challenge the supreme leader's authority and to establish his own economic network and sphere of influence.

Over the last four years, Ahmadinejad has repeatedly tried to undermine the ruling clerics' control over political and policy decisions. In 2011, he attempted to dismiss Heider Moslehi, an ally of Khamenei, from his position as intelligence chief, but was quickly overruled. He has also reduced the resources channeled to certain religious institutions, helped those in his circle to establish private banks by easing regulations, and challenged Iran's most powerful economic and military institution, the Islamic Revolutionary Guards Corps (IRGC).

But, as the rift between Khamenei and Ahmadinejad has grown, support for the president has declined significantly, with even state-run media referring to Ahmadinejad's loyalists as a "deviation circle." Moreover, unlike during Ahmadinejad's first term, non-state media now publicly criticize his economic and political agenda.

With the end of Ahmadinejad's second and final term fast approaching, it seems unlikely that the disgraced, unpopular president will abandon his efforts to destabilize Iran's ruling establishment. In fact, he had long promoted Mashai as his successor, but Khamenei curtailed his illegal efforts -- and has now put a stop to Mashai's candidacy altogether.

Mashai is among Iran's most controversial figures, widely reviled among conservative leaders for his reformist, anti-clerical views. In 2009, after Khamenei rejected Ahmadinejad's decision to appoint Mashai as his first deputy, Ahmadinejad brazenly appointed him Chief of Staff, a move that infuriated Khamenei.

Ahmadinejad is not the first high-ranking official in Iran to challenge the supreme leader. Grand Ayatollah Hossein Ali Montazeri, one of Iran's most senior clerics, would have been Supreme Leader himself had he not fallen out with Grand Ayatollah Ruhollah Khomeini, the Islamic Republic's founder, a few months before Khomeini's death.

One of the most influential figures in Iran during the Republic's first decade, Montazeri provided an extensive justification for the supreme leader's absolute authority, which many ayatollahs considered heretical. But he soon began to challenge the Islamic Republic's hardline leadership -- and continued to do so until he died in 2009.

Montazeri, whose status as Grand Ayatollah (the most senior of Shia Muslim theologians) gave him more religious authority than Khamenei, challenged Khamenei's qualifications to issue fatwas (Islamic religious rulings) or to succeed Khomeini as Supreme Leader. Montazeri was placed under house arrest for six years; demonstrations of support for him were suppressed; and many of his disciples and close friends were imprisoned, tortured, killed, or forced to flee the country.

Likewise, Abulhassan Banisadr, the Islamic Republic's first president, fell out with Khomeini over the division of authority. He was impeached in 1981, after only a year in power, and fled to France, where he continues to reside. Violent street clashes between Banisadr's supporters and opponents resulted in deaths on both sides.

In many ways, Ahmadinejad's story resembles that of Banisadr. Both were relatively unknown before their presidencies; both depended on the supreme leader's backing to gain power; and both gradually lost support as they attempted to reduce the influence of the clerical hierarchy and the IRGC. Most important, both failed to create an external organization on which they could rely if their official protection failed.

The fact that Ahmadinejad has been allowed to serve out his entire second term -- an outcome that the media often doubted -- reflects the importance to Khamenei of maintaining an image of a stable Iran. But achieving that goal will require Khamenei to account for Ahmadinejad's unpredictability.

With nothing to lose, Ahmadinejad could decide to destabilize the Islamic Republic if he considers it necessary for his survival. Indeed, now that the Guardian Council has disqualified Mashai from the presidential race, Ahmadinejad's resentment will probably manifest itself in behavior before and after the election, such as releasing information on high-level corruption. He might also oppose Khamenei directly, portraying himself as a patriotic anti-clerical figure. But such an approach would be dangerous; indeed, it could cost Ahmadinejad his life.

After the election, the kind of factional disputes that have long paralyzed policymaking in Iran will likely persist. But stalemate over Iran's nuclear policy could have serious consequences. Indeed, the lack of a strong, unified government capable of shaping a consensus could make it impossible even for Khamenei to change course, leaving Iran no choice but to persist in its diplomatic standoff with the West.

Mehdi Khalaji is a senior fellow at The Washington Institute.