Campaigning began for the Okinawa gubernatorial election on Thursday with candidates backed by the ruling and opposition parties set to clash over the contentious and long-running issue of the relocation of a key U.S. Marine Corps base within the southern island prefecture.

Reviving the all-important tourism industry is also a focus of the Sept. 11 election with the Okinawan economy having taken a heavy battering from travel restrictions put in place during the coronavirus pandemic.

Supporters rally for their candidate in Naha on Aug. 25, 2022, as campaigning for the Okinawa gubernatorial election began. (Kyodo)

Three candidates running in the election are incumbent Denny Tamaki, 62, backed by the main opposition Constitutional Democratic Party of Japan and smaller opposition parties; former Ginowan Mayor Atsushi Sakima, 58, backed by the ruling Liberal Democratic Party and its coalition ally Komeito; and Mikio Shimoji, a 61-year-old former member of the House of Representatives.

The first major election since Prime Minister Fumio Kishida reshuffled his Cabinet earlier this month could alter the course of the relocation plan.

Tamaki, who is seeking a second four-year term, is opposed to the relocation of the Air Station Futenma from the densely populated Ginowan to the Henoko coastal area of Nago, preferring instead that it be moved outside of the prefecture completely.

"I will not let a new base be built in Henoko," Tamaki said in his first stump speech in Uruma. "I will do my utmost."

Sakima, who was defeated by Tamaki in the 2018 gubernatorial race, supports the base transfer.

"I will end the U.S. base issue and pave the way for the future. I will realize the return of (the land occupied by the base in) Futenma by 2030," Sakima said at a campaign launch gathering in Naha.

Shimoji said in a YouTube video shot near the landfill site of Henoko that he will "change Okinawa," proposing to turn the base into an airport to be shared by commercial and military aircraft.

The central government maintains the current Futenma base relocation plan is the only solution that ensures deterrence under the Japan-U.S. alliance and removes the dangers posed by the base at the same time, while Okinawa wants the controversial air base moved outside the prefecture.

Chief Cabinet Secretary Hirokazu Matsuno reiterated the central government's position on the relocation plan, first agreed upon between Japan and the United States in 1996.

"We will continue to make full efforts to alleviate Okinawa's burden of hosting bases while striving to gain local understanding," he said in a regular news conference.

Okinawa still hosts the bulk of U.S. bases in the country over 50 years after it was returned to Japan from the postwar U.S. administration in 1972. The Japanese government places strategic importance on Okinawa due to its proximity to potential geopolitical flashpoints such as Taiwan, which has come under increasing pressure from a more aggressive China.

The Cabinet Office is set to request 279.8 billion yen ($2 billion) in the fiscal 2023 budget for Okinawan development, less than 299.8 billion yen for fiscal 2022, according to government sources and ruling bloc members.

Some lawmakers of the ruling camp had earlier suggested accepting a prefectural budget request for 300 billion yen or more would help Tamaki win the election.

Sakima has called for increasing the budget to 350 billion or more.

Other issues at the forefront of voters' minds include Okinawa's per capita income remaining the lowest in Japan and the problem of child poverty in the prefecture.

A warning sign on a fence in the Henoko coastal area of Nago, Okinawa Prefecture, where land reclamation work is under way for the planned relocation of U.S. Marine Corps Air Station Futenma is pictured on Aug. 24, 2022. (Kyodo)