A civic activist backed by liberal opposition has won the by-election for Seoul mayor in a race seen as a barometer of public sentiment toward the conservative government.
South Korea's National Election Commission said Thursday that independent Park Won-soon beat ruling party candidate Na Kyung-won by a margin of 7 percent in Wednesday's vote.
Top potential presidential contenders from both liberal and conservative blocs had thrown their weight behind the candidates.
The by-election came after Oh Se-hoon resigned as Seoul mayor in August over his defeat in a citywide referendum on a free school lunch program. Park will serve out Oh's remaining tenure of 2 1/2 years.
South Korea is set to hold parliamentary and presidential elections next year.