FOUR YEARS ago, voting in Iran almost triggered regime change. Millions protested President Mahmoud Ahmadinejad’s apparently fraudulent reelection over a moderately reformist opponent. The movement quickly grew into a wider challenge to the theocracy that has ruled Iran since 1979. Using arrests and violence, the country’s unelected de facto ruler, Ayatollah Ali Khamenei, eventually crushed the so-called Green Revolution — and drew the lesson that even a tiny bit of genuine political competition is too much.

Or so it appears from his regime’s behavior since 2009, which has included the vilification of even such erstwhile allies as Mr. Ahmadinejad for their policy deviations — as well as the targeting of actual dissidents for harassment, arrest and, as a United Nations human rights rapporteur put it in a March report, “torture . . . on a geographically widespread and systemic . . . basis.”

The regime’s drive for total control culminated in last week’s announcement by the Khamenei-controlled Guardian Council barring two potentially serious but hardly radical candidates, former president Ali Akbar Hashemi Rafsanjani and Mr. Ahmadinejad’s aide Esfandiar Rahim Mashaei from running in the June 14 presidential election. (The current president is limited to two terms.) What’s left is a list of eight candidates notable mainly for their fealty to Mr. Khamenei.

This heavy-handed move evoked dismay across Iran, including an open letter from the daughter of the Islamic republic’s founder, the late Ayatollah Ruhollah Khomeini. Barring Mr. Rafsanjani showed “disrespect to the wishes of the people on the street,” Zahra Mostafavi Khomeini wrote, and ran contrary to her father’s wish “to prevent dictatorship.” That accusation is more than a little ironic, given Mr. Khomeini’s dubious democratic credentials. Its importance lay in coming from such a prominent source — and in the fact that Mr. Khamenei brushed it off.

Plainly, he is no less determined to consolidate power than he is to pursue his other goals: saving the Syrian regime of Bashir al-Assad and continuing a nuclear-weapons program. Recent days have seen Iran’s Lebanese Shiite proxy, the Hezbollah militia, take the field in ever greater strength against Mr. Assad’s armed opponents, as well as a new report by the International Atomic Energy Agency documenting Iran’s expansion of nuclear enrichment — albeit still just below the levels that might cross Israel’s “red line” for a preemptive strike. Meanwhile, nuclear talks are in limbo, despite an apparent show of flexibility by the U.S.-led side toward Iran in meetings this year.

President Obama has said the United States won’t tolerate Iran developing a nuclear weapon, and his administration has imposed tough economic sanctions. It has responded with great patience to the perpetual failure of negotiations, most recently taking a wait-and-see approach pending the June 14 vote. Now that some sort of victory for Mr. Khamenei seems predetermined, it’s time to start planning for the next phase.