Iranians yearning for more freedom at home and less isolation abroad have emphatically re-elected President Hassan Rouhani, throwing down a challenge to the conservative clergy that still holds ultimate sway.Interior Minister Abdolreza Rahmanifazli announced Rouhani's victory on Saturday on state television. Rouhani secured 57 percent of the vote in Friday's election, compared to 38 percent for his main rival, hardline judge Ebrahim Raisi, according to figures cited by Rahmanifazli.Although the powers of the elected president are limited by those of unelected Supreme Leader Ayatollah Ali Khamenei who outranks him, the scale of Rouhani's victory gives the pro-reform camp a strong mandate to seek the sort of change that hardliners have managed to thwart for decades.Rouhani's opponent Raisi, a protege of Khamenei, had united the conservative faction and had been tipped in Iranian media as a potential successor for the 77-year-old supreme leader who has been in power since 1989. His defeat leaves the conservatives without an obvious flag bearer.The re-election is likely to safeguard the nuclear agreement Rouhani's government reached with global powers in 2015, under which most international sanctions have been lifted in return for Iran curbing its nuclear program.And it delivers a setback to the Revolutionary Guards (IRGC), the powerful security force which controls a vast industrial empire in Iran. They had thrown their support behind Raisi to safeguard its interests."I am very happy for Rouhani's win. We won. We did not yield to pressure. We showed them that we still exist," said 37-year-old Mahnaz, a reformist voter reached by telephone in the early hours of Saturday. "I want Rouhani to carry out his promises." Nevertheless, Rouhani stills faces the same restrictions on his ability to transform Iran that prevented him from delivering substantial social change in his first term and thwarted reform efforts by one of his predecessors, Mohammad Khatami.The supreme leader has veto power over all policies and ultimate control of the security forces. Rouhani has been unable to secure the release of reformist leaders from house arrest, and media are barred from publishing the words or images of his reformist predecessor Khatami."The last two decades of presidential elections have been short days of euphoria followed by long years of disillusionment," said Karim Sadjadpour, senior fellow at the Carnegie Endowment who focuses on Iran."Democracy in Iran is allowed to bloom only a few days every four years, while autocracy is evergreen." The re-elected president will also have to navigate a tricky relationship with Washington, which appears at best ambivalent about the nuclear accord reached by former US president Barack Obama. President Donald Trump has repeatedly described it as "one of the worst deals ever signed," although his administration re-authorized waivers from sanctions this week.Trump arrived on Saturday in Saudi Arabia, his first stop on the first trip abroad of his presidency. The Saudis are Iran's biggest enemies in the region and are expected to push hard for Trump to turn his back on the nuclear deal.TURN-OUTRouhani, known for decades as a mild-mannered member of the establishment, campaigned as an ardent reformist to stir up the passions of young, urban voters yearning for change. At times he crossed traditional rhetorical boundaries, openly attacking the human rights record of the security forces and the judiciary.During one rally he referred to hardliners as "those who cut out tongues and sewed mouths shut." In a debate last week he accused Raisi of seeking to "abuse religion for power." The language at the debate earned a rare public rebuke from Khamenei, who called it "unworthy." The contentious campaign could make it more difficult for Rouhani to secure the consent of hardliners to carry out his agenda, said Abbas Milani, director of the Iranian Studies program at Stanford University. "Rouhani upped the ante in the past ten days in the rhetoric that he used. Clearly it's going to be difficult to back down on some of this stuff." The Guards could also use their role as shock troops of Iran's interventions elsewhere in the Middle East try to derail any future rapprochement with the West, said Meir Javedanfar, an Iranian-born lecturer on Iran at Israel's Interdisciplinary Centre Herzliya."Since the 1979 revolution, whenever hardliners have lost a political battle, they have tried to settle scores," he said. "I would worry about the more confrontational policy of the IRGC in the Persian Gulf ... and more confrontational policy with the US and Saudi Arabia."Khamenei praised Iranians for their big turnout after voters queued up for hours to cast their ballots. High turnout appeared to have favored Rouhani, whose backers' main concern had been apathy among reformist-leaning voters disappointed with the slow pace of change.Many voters were particularly determined to block the rise of Raisi, one of four judges who sentenced thousands of political prisoners to death in the 1980s, regarded by reformers as a symbol of the security state at its most fearsome."The wide mobilization of the hardline groups and the real prospect of Raisi winning scared many people into coming out to vote," said Nasser, a 52-year-old journalist."We had a bet among friends, and I said Raisi would win and I think that encouraged a few of my friends who might not have voted to come out and vote." The election was important "for Iran's future role in the region and the world," Rouhani said on Friday after voting.Raisi, 56, had accused Rouhani of mismanaging the economy, traveling to poor areas and holding rallies where he promised more welfare benefits and jobs.Despite the removal of nuclear-related sanctions in 2016, lingering unilateral US sanctions that target Iran's record on human rights and terrorism have kept foreign companies wary of investing, limiting the economic benefits so far.