The Okinawa Prefectural Assembly on Friday approved a bill that will trigger a referendum on the controversial plan to transfer a key U.S. military base within the prefecture.

The move by the assembly, where a majority of members are opposed to the base transfer, came after a civic group calling for the vote collected about 93,000 signatures and filed a direct petition with the prefecture in September.

“(The ordinance) is meaningful as it enables every individual in Okinawa to express their will clearly,” said Okinawa Gov. Denny Tamaki, who opposes the relocation and won the gubernatorial election last month, in a statement.

Tokyo and Washington have been seeking to relocate U.S. Marine Corps Air Station Futenma from a crowded residential area of Ginowan to the less populated coastal district of Henoko in Nago, but many Okinawa residents want the base moved outside the prefecture.

The ordinance stipulates that a referendum should be held within six months after promulgation, and Tamaki is expected to set a detailed schedule for the vote.

The civic group claims a referendum is the most effective means to make a decision about the relocation based on the will of Okinawa residents. It collected more than four times the number of signatures required by law in two months from May.

The prefectural government submitted the bill to the assembly in late September.

To hold the referendum administrative support from municipal governments in Okinawa will be necessary, but six out of 41 municipalities in the prefecture have not yet responded to a request from the prefectural government.

Last week the Ishigaki Municipal Assembly adopted a statement opposing the referendum, arguing that “it has become a means to advocate certain political views by using public funds.”

Japan’s Local Autonomy Law calls for consultations with municipal government chiefs in establishing ordinances. If the prefectural government fails to gain support from some municipalities, it will not be possible to hold the referendum in all districts.