Former Naha Mayor Takeshi Onaga said Tuesday he will do "whatever it takes" to block the planned transfer of the Futenma U.S. military base in Okinawa Prefecture as he laid out his campaign pledges for the Nov. 16 gubernatorial election.

Onaga, whose major rival will likely be the current governor, Hirokazu Nakaima, said he will "never allow a new military base to be built in Henoko by doing whatever it takes."

The election could boil down as a referendum on Nakaima's approval last December to start landfill work off the Henoko district of Nago, a necessary step to build the new base.

"If we can find flaws, we can invalidate (Nakaima's approval). It won't take much time," Onaga said at a news conference.

He also indicated that he wouldn't approve an application submitted in September by the Defense Ministry to change part of the construction plan.

The relocation plan has been hampered by strong opposition in Okinawa, which hosts the bulk of U.S. military installations in Japan, and domestic political wrangling.

Prime Minister Shinzo Abe has pledged to ease Okinawa's burden and extend financial support in an apparent bid to move the controversial base transfer forward.

Nakaima, who has already announced his own campaign pledges, has said the current relocation plan will "surely boost the safety" of local residents, given that U.S. military aircraft are not expected to fly over residential areas after the transfer is completed. The Futenma base is located in a densely populated area in the city of Ginowan.

The election is expected to be an uphill battle for Nakaima, who is seeking a third term with the support of Abe's Liberal Democratic Party.