Iranian Supreme Leader Ayatollah Ali Khamenei attends a meeting in Kermanshah. (Office of the Supreme Leader via AP)

Iran-watchers are studiously watching Iran's political establishment for its reaction to new President Hassan Rouhani's first steps toward making nice with the United States. And so far the signs are actually quite promising, with hints of support from even the supreme leader. But some crucial hard-liners still appear skeptical; if their skepticism turns to outright opposition and the political system turns in on itself, that could kill any deal.

So far, though, for all the messy infighting of Iran's political system, Tehran has appeared surprisingly supportive. The signals are early and tentative enough that Rouhani's support in Tehran could still fall apart. But it's a positive sign for his crucial efforts to sell Iranian politics on rapprochement, and a remarkable turn after decades of deep-seated anti-Americanism.

Rouhani's historic phone call Friday with President Obama is eliciting generally positive responses in Tehran. The call was the first direct contact between an American and Iranian president since 1979; the two reportedly discussed cooperating on a nuclear deal and other "regional" issues. It was a symbolically important gesture toward rapprochement, which both presidents support but could still be derailed by hard-liners in either capital -- and especially by Supreme Leader Ali Khamenei, who is ultimately Rouhani's boss.

Even Khamenei, the most important person in the Iranian political system and an avowed hard-liner, has appeared supportive of Rouhani's outreach to the United States. In the weeks before the president's trip to New York for the United Nations, Khamenei gave speeches advocating compromise and "heroic leniency" -- signs of support for Rouhani's diplomacy and an amazing turn after years of confrontational anti-Americanism. When Rouhani landed in Tehran on Saturday, hours after his phone call with Obama, Khamenei sent his senior adviser Ali Akbar Velayati to greet Rouhani at the airport, widely perceived as a nod of support for the call.

Khamenei may be at the heart of the Iranian political system, but he is not its entirety. Despite his title, he's not all-powerful, and has proven particularly susceptible to political pressure from his right. That pressure could derail a deal.

Hard-liners are less powerful in Tehran now than they were under Ahmadinejad, but they've still got real influence – and are by far the most likely group to try to undermine any diplomatic efforts, even if Khamenei favors them. So it's just as important to watch people like Gen. Mohammad Ali Akbar Jafari, the head of Iran's powerful Revolutionary Guard Corps. In an interview with Tasmin News, Jafari reportedly offered some tepid support for Rouhani's efforts, but did say he should have "postponed" the phone call with Obama until the U.S. delivered some relief on sanctions. That's not outright opposition, but it's an early sign of what we can expect from hard-liners: "Don't compromise until they give us everything we want," which is of course a recipe for failure.

Here, from The Post's Tehran bureau, is a translation of Jafari's remarks. You can spot a bit of pressure here for Rouhani to "correct" his "mistakes." Expect that pressure to rise if diplomacy progresses:

Mr. Rouhani and his delegation on this trip showed that, thank God, they are insisting on maintaining our principles and moving on the path of Islamic Republic within the framework of the policies of our system and our leader. Our president, who had such a powerful speech at the U.N., just as he did not accept to meet with Obama, would have been better off postponing the phone call to a time after we've seen real action from the United States. On this path from our government there might be tactical mistakes, like the phone call with Obama, but they can be corrected.

Most official reactions in Tehran, though, have been positive. Qassem Suleimani, the head of the influential and hard-line Quds Force, said Rouhani's diplomacy showed how much the world respects Iran. Abdollah Javadi-Amoli, a grand ayatollah and major figure in Iran's clerical establishment, signaled support for the phone call with Obama.

Still, it's hard not to worry about people like Jafari, the Revolutionary Guards chief. In a Sunday interview on Iranian television, he seemed to raise further concerns about not just Rouhani's outreach to the United States but even about Khamanei himself, whom Jafari seemed to hint should oppose peace, comparing Iran's stand-off with the U.S. to the eight-year Iran-Iraq war. People like Jafari have real pull in Tehran; if he sees diplomacy as a danger to Iran, expect to see him using his influence more and more to undercut Rouhani, even if it means pressuring Khamenei as well.