Win or lose, local and by-elections leave their mark on ruling, opposition parties

South Korean voters handed the ruling Democratic Party of Korea a decisive victory in the local elections, but kept Seoul and much of the conservative southeast out of its reach, tempering the triumph while giving the battered People Power Party a political lifeline.

The Democratic Party won 12 of the country’s 16 mayoral and gubernatorial races, while the main opposition People Power Party secured four — Seoul, Daegu and North and South Gyeongsang provinces, the latter three in its traditional ...