An anti-nuclear candidate was elected governor of Niigata on Sunday, dealing a potential blow to Tokyo Electric Power Co.'s attempts to restart the world's biggest nuclear power station.

The winner, Ryuichi Yoneyama, 49, is a doctor and lawyer who has never held office and was backed mostly by left-wing parties.

The campaign was dominated by concerns over the future of the massive Kashiwazaki-Kariwa power station and nuclear safety more than five years after the Fukushima crisis.

Yoneyama defeated former Nagaoka Mayor Tamio Mori, 67, who was backed by the pro-nuclear Liberal Democratic Party.

Yoneyama gathered more than 528,000 votes, about 60,000 more than Mori. Voter turnout was 53.05 percent, up significantly from the 43.95 percent in the previous gubernatorial election in 2012.

"It's really regrettable. We will take the judgment of voters very seriously," said Keiji Furuya, a Lower House member who served as head of Mori's campaign office.

Yoneyama promised to continue the policy of the departing governor, who had long thwarted Tepco's ambitions to restart the plant.

Reviving the seven-reactor giant, with capacity of 8 gigawatts, is key to saving the utility, which was battered by the Fukushima catastrophe of March 2011 and then the repeated admissions of coverups and safety lapses.

Tepco is vital to Prime Minister Shinzo Abe's energy policy, which relies on rebooting more of the reactors that once provided about 30 percent of the nation's electricity needs.