All eligible voters in Okinawa will be able to take part in a referendum on the relocation plan for a key U.S. air base later this month, as three cities that were opposed to it announced Friday they have changed their position.

The Feb. 24 referendum will ask people to vote on the controversial U.S.-Japan plan, with Gov. Denny Tamaki hoping its outcome, although not legally binding, will further demonstrate Okinawa’s opposition to the project.

The current ordinance on Okinawa referendums calls on governors to respect outcomes supported by at least a quarter of eligible voters.

Five cities, including the final three holdouts, had objected to the original referendum plan, in which voters would cast ballots of only “yes” and “no” on the transfer of U.S. Marine Corps Air Station Futenma from a crowded residential area of Ginowan to the less populated coastal area of Henoko in Nago, arguing that residents have various opinions on the matter.

After the prefectural assembly passed a bill on Tuesday to revise the ordinance on the referendum and allow voters to pick “neither,” two mayors expressed their willingness by Thursday to take part. They were followed by the other three on Friday.

Ishigaki Mayor Yoshitaka Nakayama told reporters, after the municipal assembly on Friday adopted a budget related to the vote, that the city will cooperate with the prefecture on the poll.

Ginowan Mayor Masanori Matsugawa said his city values the addition of the third choice for voters.

“I appreciate that some assembly members who had been against (the referendum) finally showed understanding,” Okinawa Mayor Sachio Kuwae said.

“I think the Okinawa people are very pleased” with the cities’ decision, Tamaki told reporters.

Tamaki, who won a gubernatorial election last September on an anti-base platform, had feared a low turnout could undermine the validity of the referendum results, and had urged the five cities to join the vote.

Some of the five municipalities had initially said they would take part if the prefectural assembly unanimously approved a revision of the ordinance.

As there were objections to the bill from some Liberal Democratic Party members close to the central government’s policy of pushing forward the planned base relocation, it was unclear whether the referendum would cover all eligible voters.

Many residents of Okinawa, which hosts the bulk of U.S. military facilities in Japan, are frustrated with noise, crime and accidents linked to them and want the Futenma base to be moved outside the prefecture.