South Korea's ruling Democratic Party (DP) swept Wednesday's local and parliamentary by-elections, winning 12 of 16 key mayoral and gubernatorial races and nine of 14 National Assembly seats, delivering a powerful mandate to President Lee Jae-myung at the start of his second year in office. The result marks a dramatic reversal from the previous local elections in 2022, when the conservative People Power Party (PPP) had claimed 12 of 17 major positions. Voter turnout reached 61 percent, some 11 percentage points higher than four years ago, signalling heightened public engagement.
Among the most symbolic victories was the DP's capture of Busan, South Korea's second-largest city and a traditional conservative stronghold in the country's southeast. DP candidate Jeon Jae-soo, a former minister of maritime affairs, defeated PPP incumbent Park Heong-joon by a slim margin. In Gyeonggi Province — the densely populated region surrounding Seoul that is home to roughly half the country's population — veteran DP lawmaker Choo Mi-ae became the first woman ever to head a provincial government in South Korea. The PPP retained the Seoul mayoralty, where incumbent Oh Se-hoon won a fifth term, and held onto the handful of regions where conservative voters have maintained unconditional support for decades, including the city of Daegu in North Gyeongsang Province, a diehard conservative heartland.
The elections were widely read as the first nationwide verdict on Lee's administration, which took office on June 4, 2025 following a snap presidential election. Lee had come to power after the ouster of former President Yoon Suk-yeol, who declared martial law in December 2024 in a move widely condemned as unconstitutional. Yoon was subsequently sentenced to life imprisonment for insurrection. The DP campaigned on consolidating stability after that political crisis, while the PPP sought to portray the vote as a check on unchallenged liberal rule. Political analysts noted that the PPP's failure to credibly distance itself from Yoon's legacy, combined with Lee's consistently high approval ratings of around 60 percent, made a DP victory broadly anticipated — though the narrow margins in Seoul, Busan and Daegu suggested voters were distinguishing between support for the president personally and enthusiasm for the party as a whole.
The vote was not entirely without controversy. Fourteen polling stations in parts of Seoul temporarily ran out of ballot papers, prompting brief suspensions of voting. The National Election Commission's secretary general issued a public apology. The PPP called on authorities to halt vote counting and consider a revote in affected areas. Observers noted that the PPP has a history of making allegations of electoral irregularities following defeats — claims consistently dismissed by courts and independent bodies.
The landslide result is expected to strengthen Lee's hand as he pushes forward a reform agenda that includes judicial changes, industrial transformation centred on artificial intelligence, and measures to manage economic pressures linked to regional conflicts. The DP's reinforced dominance in local government, combined with its existing majority in the 300-member National Assembly, puts the ruling party in a commanding position heading into the second year of Lee's single five-year term.