TEHRAN — After many Iranians skipped voting in Friday’s presidential election, seeing it as rigged in favor of an ultraconservative contender, that candidate — the hard-line judiciary chief, Ebrahim Raisi — won Iran’s presidency Saturday, paving the way for the country’s leadership to cement the conservative legacy of the supreme leader, Ayatollah Ali Khamenei.

Raisi, 60, a cleric favored by Khamenei, has been seen as the supreme leader’s possible successor. With his election, the ayatollah will finally have a president all but guaranteed not to challenge him, leaving the urban middle classes who have consistently supported social reforms and engagement with the outside world with no voice at the top.

Raisi has a record of grave human rights abuses, including accusations of playing a role in the mass execution of political opponents in 1988. Yet his background appears unlikely to hinder the renewed negotiations between the United States and Iran over restoring a 2015 agreement to limit Iran’s nuclear and ballistic missile programs in exchange for lifting American economic sanctions. Raisi has said he will remain committed to the deal.

The Interior Ministry said Saturday that Raisi had won with nearly 18 million of 28.9 million ballots cast in the voting a day earlier. Turnout was 48.8 percent — a significant decline from 2017, when the country’s moderate- and liberal-leaning voters powered the reelection of President Hassan Rouhani, a centrist pragmatist whose administration negotiated the first nuclear deal with the United States.