Denny Tamaki, who was backed by opposition parties, soundly defeated Atsushi Sakima, who ran with the support of Abe's Liberal Democratic Party and its junior coalition partner, the Komeito, official results showed.

Public broadcaster NHK showed a jubilant Tamaki and his supporters cheering and dancing after news of his victory.

Sakima's defeat is a blow for Abe, as the Okinawa vote was the first high-profile election after the premier won a Sept. 20 LDP leadership vote, putting himself on track to become Japan's longest-serving premier.