(CNN) Iranian President Hassan Rouhani handily won re-election in what is a victory for the Shiite nation’s reformist camp and a sign that citizens favour fruitful engagement with the outside world.

Rouhani, who defeated his conservative challenger Ebrahim Raisi in the Friday elections, garnered 57% of the vote, said Interior Minister Abdolreza Rahmani Fazli. He’ll serve another four years in the post.

“The National Media (IRINN) congratulate the victory of Mr. Hassan Rouhani in the presidential election,” Iranian state media channel IRINN announced in an on-screen news ticker.

Rouhani, a moderate, was a key architect of the 2015 nuclear deal with the United States, the European Union and other partners, and his first term was marked by an emergent international outreach.

The agreement has been controversial in both the United States and Iran and it emerged as a top campaign issue, with the election seen in part as a referendum on the agreement.

More than 40 million Iranian voters flocked to polling stations Friday, according to the head of Iran’s Interior Ministry State Elections Committee.

Iran’s Supreme Leader Grand Ayatollah Ali Khamenei — who praised the turnout — was among the first to cast his ballot and urged others to do the same.

“I believe that the presidential election is very important. The fate of the country is in the hands of people,” he said.