Anti-base candidate Susumu Inamine has been re-elected mayor of Nago city, in Okinawa prefecture in southern Japan, by a sizeable margin, according to the latest poll projections by the Japanese media.
Voting ended at 8 pm (Japan time) today and full results are not expected until later tonight.
But based on the results of pre-election and exit polls, the Japanese media have already reported that Mr Inamine has safely won re-election.
The closely watched election held today was fought over the proposed use of Nago's beach-fronted Henoko district to build a United States air base.
Mr Inamine, 68, beat his only rival, pro-base Mr Bunshin Suematsu, 65, who was supported by Prime Minister Shinzo Abe's ruling Liberal Democratic Party (LDP).
Mr Inamine's victory puts a question mark on the Tokyo government's hopes of implementing a long-standing pact made with its security ally Washington to relocate the US Futenma air base, also in Okinawa, to the Henoko area.
Mr Inamine had indicated that if he was re-elected, he would use his mayoral authority to block a proposed landfill project at Henoko for the new air base.
Futenma is located in the southern part of Okinawa island, smack in the middle of densely populated Ginowan city.
Ginowan residents want the base moved elsewhere because of the constant noise and physical danger posed by US aircraft landing and taking off at the facility.