A majority of voters in a closely-watched referendum on the Japanese island of Okinawa have reportedly rejected a controversial plan by the government to relocate and expand a US military base there.

According to exit polls cited by the local media on Sunday, more than 70 percent of Okinawan voters opposed the relocation and expansion of the US Marines’ Futenma air base to a remote part within the prefecture.

Japan’s Asahi Shimbun newspaper reported that the overall ballots cast by opponents to the project could top the record 396,632 votes that put Okinawa Governor Okinawa Governor Denny Tamaki into office last September.

Tamaki campaigned against and remains staunchly opposed to the plan.

Official results are expected late Sunday or on Monday.

The central government’s plan requires the US air base — which is currently located in a busy and densely-populated part of Okinawa — to be moved to the remote coastal region of Henoko in Nago, some 50 km away.

Opponents of the move say the relocation of the base will not only threaten the area’s delicate marine ecosystem but also endanger its 2,000 local residents.

The administration of Prime Minister Shinzo Abe has vowed to press on with moving the base and the relocation is also backed by Washington. Tokyo’s government and Okinawa authorities have been at loggerheads over the plan to move the US base.

The relocation of Futenma to Nago was first agreed in 1996 as the US sought to calm local anger after US servicemen gang-raped a local schoolgirl. But the plan has long been stalled in part over local opposition.

Many Okinawa residents associate the bases with crime, pollution, and accidents and want the base off the island altogether.

On Friday, more than 100 activists tried to block trucks entering the construction site at Nago.

“We hope the referendum will boost the momentum of our fight,” demonstrator Masaru Shiroma told AFP ahead of the referendum on Friday, adding, “The government is making a fool out of Okinawa.”

Okinawa hosts more than half of the approximately 47,000 American military personnel stationed in Japan. It makes for 64 percent of the land used by the US bases under a bilateral security treaty rooted in imperial Japan’s defeat in WWII.