Hassan Rouhani’s victory in Iran’s presidential elections last month has been greeted with euphoria among Iranians and cautious optimism from Western diplomats, with an overriding sense of relief uniting the two camps. Relief among Iranians that they won’t face another four years with an Ahmadinejad Mark II in Iran’s chief nuclear negotiator, Saeed Jalili (who was expected to win but beaten into third place), and relief among the P5+1 (the five Security Council powers and Germany) that a Rouhani victory might finally see progress on stalled nuclear talks with Iran.

Rouhani set the tone early, and his words were encouraging: “I thank God that once again rationality and moderation has shone on Iran,” he declared. “This victory is a victory for wisdom, moderation and maturity . . . over extremism.”

Which is what everyone wanted to hear. But what is Rouhani actually likely to do? To answer the question we first need to understand how he won. He undoubtedly ran an astute campaign, making effective use of social media and timing his late surge perfectly, but he owes much of his victory to two former presidents: Akbar Hashemi Rafsanjani and Mohammad Khatami.

Rafsanjani is one of the most powerful men in the history of the Islamic Republic. He still retains great power in Iran but since Ahmadinejad’s 2009 fraudulent re-election his outspoken criticism of the regime has brought him into conflict with its most senior members. It was no real surprise (surely even to Rafsanjani himself) when the Guardian Council barred him from standing for president when he registered his candidacy in May. The Supreme Leader, Ali Khamenei, it seemed, would not tolerate anyone that might prove a focal point for opposition. But “Akbar Shah” is not so easily beaten—still keen to be a player in the elections, he chose to publicly endorse Rouhani, who gratefully accepted both his favor and the votes of his many followers.

The sheer strength of support for Rouhani was only revealed, however, when Mohammad Reza Aref, the one genuinely reformist candidate in the race, withdrew after another ex-president, Mohammad Khatami, publicly urged him to get behind Rouhani to avoid splitting the reformist vote. The hardliners, meanwhile, spread their votes among several candidates and lost the election.

Rouhani is no reformist—he is cleric who enjoys good relations with Khamenei. But he is less conservative than the Supreme Leader and, whether he likes it or not, he is now the face of a reformist-minded coalition containing some of the most influential men in Iran.

That is what stands behind him. But what type of politician is Rouhani? Much has been made of his ‘moderate’ credentials—he has certainly signaled a change of diplomatic tone. If his early rhetoric as president-elect is anything to go by, the days of Ahmadinejad’s Israel and America-baiting may be over. His talk of a more independent press in Iran and better relations with the West is reminiscent of the reformist-minded Khatami, which is also positive.

But more important than his words are his political achievements and to consider these adequately we need to go back to late 2003, just over a year after an Iranian opposition group, the MKO, publicly revealed full details of two nuclear facilities in Iran and began the nuclear crisis.

It was a fraught time. Washington had only recently deposed Saddam for the supposed crime of possessing WMDs and the Iranians feared they might be next. In September 2003 the Foreign Ministers of France, Germany and the UK went to Tehran to try to do a deal: they wanted Iran to suspend uranium enrichment. Khamenei was against a suspension of any kind—something Rouhani knew. But after two hours of negotiations it became clear to him that a settlement of some kind was needed. He took the decision, largely on his own initiative (though in the end the Supreme Leader did not oppose him) to suspend uranium enrichment, which Iran subsequently did for two years.

Rouhani can compromise, which is something Iran now needs to do more than ever. The country is suffering. Banking sanctions have damaged its access to international financial markets and the sanctions on its oil have drastically reduced the country’s foreign exchange earnings. Rising inflation and a falling currency have compounded the misery of ordinary Iranians—even traditionally conservative sections of society like the Bazaar (merchant) classes are unhappy. Rouhani needs to find some way to lessen at least some of the pressure on Iran—if only for the regime’s sake.

During Rouhani’s election campaign thousands of Iranians took the streets wearing his purple colors, but even more were wearing the green of 2009’s defeated candidate Mir-Hossein Mousavi. The message is clear: the people want change, just as they did four years ago. It won’t be easy; the President does not run the country—the Supreme Leader does. But Rouhani knows he must try to bring at least some improvement to their lives, however small.