(ATTN: RECASTS headline, lead; UPDATES with more info throughout)
SEOUL, June 14 (Yonhap) -- The ruling Democratic Party (DP) won a landslide victory in Wednesday's local elections, sweeping at least 13 of the 17 big races, including those for Seoul mayor and Gyeonggi Province governor, in what will be a big boost to President Moon Jae-in.
The DP is also certain to win at least 10 of the 12 parliamentary seats in by-elections held simultaneously with local elections, according to the National Election Commission (NEC).
The results are expected to enhance Moon's mandate for liberal reforms and engagement with the North.
The main opposition Liberty Korea Party (LKP) suffered a crushing defeat, as it won only two of the big mayoral and gubernatorial races.
At stake in the local elections were 4,016 local administrative, legislative and educational posts, including 17 big-city mayoralties and provincial governorships.
The quadrennial local elections were largely seen as a barometer for voter sentiment toward Moon, who took office in May last year.
The DP's big victory was widely anticipated, as the liberal party has basked in a high public approval rating aided by strong support for Moon and his drive for peace with North Korea.
The party also appeared to benefit from the mood for rapprochement that was created over a historic summit between the United States and North Korea in Singapore just a day earlier.
The DP expressed joy as its landslide victory has become certain.
"Today will be recorded as a day of victory for the people like last year's presidential election," Back Hye-ryun, a spokeswoman for the DP, said.
She added that Wednesday's elections reflected voters' aspirations for peace and prosperity and strong provincial governments.
Stung by a potential defeat, Hong Joon-pyo, the chief of the LKP, hinted at the possibility of his resignation from the post.
"The buck stops here," Hong wrote on his Facebook.
The conservative LKP's crushing defeat pointed to low public trust in the party, which is still reeling from the fallout of last year's ousting of former President Park Geun-hye due to a corruption scandal. The party hoped to pick up the votes of "shy" conservatives who had maintained a low profile.
Smaller opposition parties, including the center-right Bareunmirae, failed to secure chief posts in the 17 wide-area local entities.
The biggest battleground was Seoul, in which 20 percent of the country's population of 52 million lives. The Seoul mayorship carries extra weight as it is often deemed a steppingstone to the presidency.
Incumbent Mayor Park won the election for a third term against Kim Moon-soo of the conservative LKP and Ahn Cheol-soo of the minor opposition Bareunmirae Party.
Park called his election a great victory of Seoul citizens.
"I will make Seoul a city full of peace and prosperity ... The Seoul city government will back up the success of the Moon administration," he said.
As for the gubernatorial race for Gyeonggi Province, Lee Jae-myung of the DP won the seat, against Nam Kyung-pil of the LKP.
Prior to the elections, Lee was under fire following his rival's revelation that he allegedly committed adultery with an actress some years ago while pretending not to be married. But the election results showed that the scandal was not a decisive factor.
After a neck-and-neck race, Kim Kyoung-soo of the DP is certain to win the race for South Gyeongsang provincial governor against Kim Tae-ho of the LKP. The province is a traditional conservative stronghold.
Kim has been dogged by an online opinion rigging scandal that centers on allegations that Kim knew and communicated with a power blogger known by the nickname Druking, who allegedly rigged online comments on news stories in a bid to sway public opinions on hot-button political issues.
Tentative turnout for the local elections was tallied at 60.2 percent, as 25.8 million of 42.9 million eligible voters cast ballots, according to the election watchdog. It marked the first time that the voting rate in a local election surpassed 60 percent since 1995.
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