Analysis: Khamenei's death leaves Iran with no clear successor, will the clerical leadership survive?

The death of Iran's Supreme Leader Ali Khamenei in joint U.S.-Israeli attacks has plunged the Islamic Republic into its most severe leadership crisis since the 1979 revolution, raising questions about the long-term survival of its clerical system.

Iranian state media confirmed Khamenei's killing during strikes that targeted his office in Tehran on Saturday, along with other high-ranking officials. The country has declared 40 days of mourning and launched retaliatory missile and drone attacks on Israel and U.S. bases in the region.

A transitional leadership council has quickly assumed control in line with constitutional provisions. It comprises President Masoud Pezeshkian, judiciary chief Gholamhossein Mohseni-Ejei, and a representative from the Guardian Council, a powerful vetting body. This interim body is tasked with governing until the Assembly of Experts, a panel of clerics, selects a permanent successor. Ahmad Vahidi, a former defense and interior minister, was also appointed as the commander of the Islamic Revolutionary Guard Corps (IRGC) soon after the killing of his predecessor.

The swift activation of these mechanisms speaks to the institutional resilience built into Iran's clerical framework. Core pillars such as the IRGC and the Guardian Council seem to remain intact and operational, providing continuity despite the absence of a designated heir.

No single figure has emerged as a clear successor, with potential names including Khamenei's son Mojtaba, judiciary head Ejei, Ali Larijani, an advisor to the supreme leader, and senior clerics like Alireza Arafi and Mohsen Araki.

While the death of Khamenei, a pragmatic capable of navigating factions within Iran's ruling circle, has cracked open the possibility of a power struggle among the ruling elite, the ongoing military conflict might otherwise consolidate support – at least in the short term. External aggression from the U.S. and Israel has narrowed space for political division, fomenting a wartime urgency that aids the power transition.

Historically, external threats have often acted as a powerful unifying force in Iran. During the Iran-Iraq War of the 1980s, the Islamic Republic faced significant internal challenges but was able to consolidate nationalist sentiment through a shared sense of resistance against Saddam Hussein's invasion. The war not only rallied various factions within the leadership but also provided a rallying cry for the population, with the new clerical government casting itself as the defender of Iran's sovereignty. Similarly, U.S. demands for Iran to abandon its right to peacefully develop its nuclear program have been portrayed by officials as an affront to the nation's dignity and sovereignty, which has often served as a unifying cause in the past.

Earlier on Sunday, thousands of Iranians gathered in Enghelab Square in Tehran to mourn the late supreme leader, as men were seen embracing each other and weeping outside shuttered storefronts.

Iran's secular political bodies, elected by the public, have demonstrated a firm resolve to resist U.S. and Israeli aggression. Pezeshkian, who is widely viewed as a reformist not closely tied to the clerical establishment, called Khamenei's assassination "an open declaration of war against Muslims, and particularly against Shiites, everywhere in the world."

Iran considers it its "legitimate duty and right to avenge" the country's "highest authority," he said in a statement on Sunday.

Khamenei's demise has sparked fierce response among Shiite communities in several countries. In Pakistan, violent clashes erupted as hundreds of Shiite protesters tried to storm the U.S. Consulate in Karachi on Sunday, resulting in at least 9 deaths from police fire, while peaceful demonstrations occurred in Lahore, Multan, and other cities with anti-U.S. and anti-Israel chants. Pro-Iran demonstrators also gathered near the heavily fortified Green Zone in Baghdad, attempting to approach the U.S. Embassy amid clashes with security forces. In Indian-controlled Kashmir and other parts of India, large Shiite crowds took to the streets carrying portraits of Khamenei and waving black flags.

Grand Ayatollah Ali al-Sistani, a towering voice in the Shiite world, has called on Iranians to "preserve their national unity" and deny "aggressors their malicious aims" amid what he described as "difficult and sensitive circumstances."

Yet beneath this show of solidarity, Iran faces deeper fractures. Years of economic decline, partly a result of U.S. sanctions, have fueled growing public dissent against the clerical system. In the weeks prior to Tehran's standoff with Washington, protests had spread across the country, sparking deadly clashes between demonstrators and security forces before the unrest largely subsided in mid-January. Although the U.S.-Israeli strikes have left Iran's leadership shaken, opening a door – one the Trump administration clearly hopes to walk through – for protests to flare up again, so far there's no sign of demonstrations returning to the nationwide scale of January. 

Meanwhile, opposition groups face significant hurdles in capitalizing on the moment. Exiled figures like Reza Pahlavi, son of the last shah, have called for uprisings and urged military defections, framing Khamenei's death as the establishment's end. The People's Mojahedin Organization of Iran (MEK) and ethnic minority armed groups maintain advocacy abroad but lack unified structures or strong domestic networks. Ideological divisions among other domestic dissidents are loosely organized, failing to mount a coordinated challenge.

Many Iran observers have described the U.S.-Israeli campaign as an existential threat to the survival of the clerical government, but Washington's unwillingness to get bogged down in a prolonged conflict limits the prospects for immediate collapse. The U.S. approach under President Donald Trump has involved targeted escalation rather than full-scale ground invasion. Strikes have focused on leadership assassination and nuclear-related sites, distinct from ground occupations seen in past conflicts like Iraq. With U.S. midterm elections approaching later this year, domestic anti-war sentiment and the need to maintain political support constrain options for broader military commitment.

As tensions further escalate amid active hostilities, the coming weeks will test whether Iran's clerical institutions can navigate the succession. While the system has demonstrated short-term adaptability, the absence of an undisputed leader and persistent external pressure leave the system's future uncertain.