SEOUL - South Korea's ruling liberal Democratic Party won a sweeping victory in the local elections, election watchdog data showed Thursday.

With almost all votes counted, the Democratic Party won 12 out of 16 races for metropolitan mayors and provincial governors, including Gyeonggi province, the western port city of Incheon, the southeastern port city of Busan, as well as South Jeolla Province and North Jeolla Province, home turf for the liberal bloc, according to the National Election Commission.

The main conservative opposition, the People Power Party, secured the remaining four races for mayors and governors, including the capital Seoul, the southeastern inland city of Daegu, as well as South Gyeongsang and North Gyeongsang provinces, strongholds for the conservative bloc.

The Democratic Party secured nine parliamentary seats out of 14 by-elections, and the People Power Party gained four. One independent candidate was elected in Busan.

The local elections were widely seen as a confidence vote for the government of President Lee Jae-myung, which entered its second year.

Driven by Lee's popularity, the Democratic Party showed a nationwide dominance in the quadrennially held elections.

Polls by local pollster Realmeter showed that Lee's approval rating stood firm around 60 percent in recent months.