Rouhani's resounding win came despite his failure to deliver the economic revival he'd promised in 2013. Raisi, a former judge was hated across the Shia Majority country for his sentences executing thousands of political prisoners in 1980s. The turnout of the voters for that year was 73 percent. Election officials extended voting hours at least three times. Reporting from Tehran, Euronews' Javad Montazeri said: "Rouhani's outstanding number of votes are a show of firm support for him and his future government, to follow the route that's been started".
The Saudis are a strong USA ally and arch-enemy of Iran; the largely Sunni Saudis strongly opposed President Obama's outreach and nuclear deal with the Persian Shia power.
Under Rouhani, Iran reached a landmark 2015 nuclear agreement that capped Iran's nuclear activities in return for the lifting of worldwide economic sanctions.
President Donal Trump, for his part, is in Riyadh, where "the Saudis are hosting an Arab Islamic American Summit with leaders from dozens of Muslim countries", and where "Trump and the Saudi king signed several agreements spanning diplomatic, governmental and commercial ventures, including an arms deal worth $110 billion", as NPR reports.
Rouhani has been seen as a reformer in Iran's largely conservative society, and embraced modest efforts to reach out to the rest of the world in his first term.
While Mr Rouhani is a relative moderate, Iran remains a harshly authoritarian country where civil liberties are trampled.
Iran denies any involvement in terrorism and says its missile programme, which U.S. President Donald Trump recently targeted with new sanctions, is purely for defence purposes.More news: FBI's Russian Federation probe implicates top White House official
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On Saturday, Iran's Supreme Leader Ayatollah Ali Khamenei thanked the nation for "mass turnout" in the election on Friday.
Joyful voters cast their ballots for the presidential election at a polling station in Tehran, Iran, Friday, May 19, 2017.
During the campaign, he openly criticized hard-liners and Iran's powerful Revolutionary Guard, a paramilitary force involved in the war in Syria and the fight against Islamic State militants in neighboring Iraq.
At recent rallies, his supporters chanted for reformist leaders who have been under house arrest since 2011.
But he did not congratulate Mr Rouhani for his victory. No woman has ever been approved to run for president.
He emphasized that the Iranians' decisive vote throughout the country proved that they were "one nation" that had "one administration" and wanted "one president", who would be the president of all people and, of course, serve all people.
Ahmadi said the Interior Ministry hopes to have final results later Saturday.