Shariatmadari says frankly that he doesn’t believe in compromise with the West. “The identity of both sides is involved in this conflict,” says the stern editor. “It didn’t ‘just happen.’ It is structural. The problem will be solved when one side gives up its identity, only then.”

The Kayhan editor is using his powerful voice to resist the deal being negotiated by President Hassan Rouhani and Foreign Minister Mohammad Javad Zarif. He says bluntly that he doesn’t think Iran should have signed the six-month freeze negotiated last month in Geneva, and he argues that Zarif misled Rouhani and Supreme Leader Ali Khamenei when he said the deal guaranteed Iran’s right to enrichment of uranium. “This gentleman [Zarif] did not tell the truth,” he asserts.

Can hard-liners such as Shariatmadari and the leaders of the Iranian Revolutionary Guard Corps block a deal? An Iranian banker may have been right when he told me that “Zarif has the backing of 90 percent of the people” to negotiate an agreement that removes economic sanctions and eases Iran’s isolation. But the vanguard represented by Shariatmadari and the Revolutionary Guard may hold the commanding heights.

The power of the Revolutionary Guard is a crucial variable. Rouhani told me in an interview in New York this September that he thinks security organizations such as the Revolutionary Guard should have less power in Iran, and he made that argument to Iranians in June’s presidential election. But when I ask Shariatmadari about Rouhani’s critique, he dismisses it as “election propaganda.”

Tehran this week seemed a city caught somewhere between Pyongyang and Los Angeles. It’s a sprawling city with sophisticated, outgoing people. The slogans of the 1979 Islamic revolution are fading on the walls, literally.

But the radical roots of the regime are still intact. And Shariatmadari speaks for the vanguard that has internalized the message of a massive mural on Karim Khan Zand Boulevard, near his office, that shows founder Ayatollah Ruhollah Khomeini with the words: “We will never put down the flag you raised.”

A visit here makes clear that in the nuclear negotiations Iran is facing, as Shariatmadari says, an internal struggle over its identity. That’s evident in the public sniping between Zarif and his critics, including the Revolutionary Guard chief, Maj. Gen. Mohammad Ali Jafari. The Iranian leadership may be allowing this debate to heighten its leverage in negotiations — to encourage concessions to sympathetic moderates who are battling hard-liners. But it’s not just for show: You can feel the underlying tension in ordinary conversation.

The public’s support for Rouhani stems in part from national fatigue after eight years of inflammatory former president Mahmoud Ahmadinejad. He seemed to delight in shocking the West with his anti-Israel diatribes, but for many Iranians he was an embarrassment. A half-dozen people I talked to here said the Ahmadinejad years are remembered for bad economic policies and corrupt favoritism for the power elite.

The public gave Rouhani a 51 percent majority in a six-candidate field, and if he ran again, he would do far better, argues Saeed Laylaz, a prominent economic journalist, in an interview at his apartment in northwest Tehran. “We support him unconditionally,” he says, but there’s no polling data that confirm that support. As for the supreme leader, Laylaz expresses a view I also heard from others that “Khamenei is behind Rouhani because otherwise the system will collapse.”

The public yearning to escape the drabness of the Islamic republic is evident in small things. One Iranian tells me about the new fad of traveling to Sulaymaniyah in Iraqi Kurdistan and paying $100 a ticket to hear pop-music stars who can’t come to Iran. There’s also a boom in low-cost travel to less restrictive societies. Dubai and Istanbul, which used to be favorites, have gotten so expensive that Iranians out for a good time are turning to cheap flights to Yerevan in Armenia and Tbilisi in Georgia.

Shariatmadari thinks these Western temptations are poisonous. He’s suspicious even of President Obama’s phone call to Rouhani in September, which he saw as an attempt to demean Iran. I ask if Rouhani should have hung up. “We believe in politeness,” he says with a rare smile.