Former opposition lawmaker Denny Tamaki is set to defeat a candidate backed by the ruling coalition in the Okinawa gubernatorial election Sunday in which the central government's plan to relocate a U.S. base within the island prefecture was the main issue, according to Kyodo News projections.

The victory of Tamaki, 58, over the former Ginowan mayor Atsushi Sakima, 54, will be a blow to the administration of Prime Minister Shinzo Abe who is pushing the controversial base transfer plan.

"I definitely support the prefecture's retraction of approval for landfill work (necessary for the U.S. base transfer)," Tamaki told reporters in Naha shortly after media projected his win.

(The Futenma air base)

Sakima and Tamaki were the major contenders in the four-person race for the seat left vacant by Takeshi Onaga, who died of cancer in early August and was a staunch opponent of the central government's base relocation plan.

Sakima told reporters he emphasized the need to improve the life of Okinawa residents, but "it didn't quite get through to people."

With Tamaki having pledged to follow in the steps of Onaga who wanted the relocation facility off Okinawa, the election result could have an impact on the course of the plan to move U.S. Marine Corps Air Station Futenma from a crowded residential area of Ginowan to the less populated coastal district of Henoko in Nago, both in Okinawa.

Tamaki, a radio personality-turned-politician who served as a House of Representatives member for the opposition Liberal Party, has highlighted that he was designated by Onaga as his successor. He was backed by four other opposition parties and a parliamentary group.

(A U.S. base construction site in Henoko)

Tamaki, whose father was a U.S. military personnel he never met, is a native of Okinawa.

Sakima received support from the ruling Liberal Democratic Party led by Abe and its junior coalition partner, Komeito, with the opposition Japan Innovation Party also behind him.

Abe told his party's election strategy head Ryu Shionoya during their telephone conversation he was "disappointed, but it cannot be helped," according to Shionoya.

LDP Secretary General Toshihiro Nikai said, "We will look at this judgement made by the people of Okinawa sincerely, analyze why we lost and make efforts to meet (Okinawa residents') expectations."

Voter turnout was 63.24 percent, down 0.89 point from the previous election.

Both candidates had emphasized the importance of the prompt closure of the Futenma base which they say poses a danger to nearby residents, and the return of its site to Japan.

Regarding construction of a replacement facility in Nago, they adopted different approaches.

Tamaki stated his opposition to the base relocation to the coastal area in Nago, while Sakima did not clarify his stance on it during the campaign, aware that the majority of locals hope the base will be moved outside Okinawa.

The other candidates who ran were Hatsumi Toguchi, an 83-year-old former Naha city assembly member and expert on local cuisine, and 40-year-old Shun Kaneshima, a former internet technology firm employee who runs a restaurant.

Following Onaga's instruction in July, the prefectural government retracted after his death its approval for landfill work necessary for the relocation, claiming illegality in the application process and halting construction work by the Defense Ministry.

According to local political sources, Onaga recorded a voice message shortly before his death designating Tamaki and local businessman Morimasa Goya as possible successors, but the message has not been made public. After that, Tamaki decided to run in the election, while Goya has expressed support for Tamaki.

Meanwhile, former Deputy Ginowan Mayor Masanori Matsugawa, 65, was assured of victory in the Ginowan mayoral election held the same day to pick a successor to Sakima, defeating company executive Harumasa Nakanishi, a 57-year-old former head of a union of Okinawa high school parent-teacher associations.

In a similar picture to the gubernatorial race, Nakanishi, tapped by local members of the opposition Japanese Communist Party and the Social Democratic Party, has expressed opposition to the base relocation plan within Okinawa, while Matsugawa, backed by the LDP-led coalition, did not clarify his stance.

Earlier this month, the Nago city assembly election was held, in which candidates opposed to the base relocation plan secured a majority.

The Futenma relocation, first agreed on between Japan and the United States in 1996, has been a sensitive issue in Okinawa. The island prefecture, which was under U.S. control between 1945 and 1972 following Japan's defeat in World War II, hosts the bulk of U.S. military installations in Japan.