SEOUL, June 4 - South Korean President Lee Jae Myung's ruling Democratic Party swept most major local races in elections held on Wednesday, but suffered a symbolic setback as the opposition conservative incumbent Oh Se-hoon won another term as Seoul mayor.

The Democratic Party won 12 of the 16 major mayoral and provincial contests nationwide, while the conservative People Power Party won four, a result that gives Lee's party broad control of local governments a year into his presidency.

The loss of Seoul, South Korea's largest city and its most politically prized mayoralty, however, tempered the ruling party's victory and gives conservatives a key foothold as they seek to rebuild after the scandal over former President Yoon Suk Yeol's failed 2024 martial law bid and subsequent impeachment.

Speaking on the one-year anniversary of his inauguration, President Lee said the government would "humbly accept the will of the people", and work actively with local governments regardless of their party affiliation.

Democratic Party leader Jung Chung-rae thanked voters for what he called a "great victory" nationwide, but acknowledged the sting of losing the capital.

"I deeply thank the people for giving the Democratic Party a great victory across the country. But it hurts that we failed to retake Seoul," Jung said.

In his victory speech, Oh said Seoul voters had upheld "the great democratic principle of checks and balances" to prevent the country from tilting entirely to one side.

"The key question was who would win symbolic battlegrounds such as Seoul and Busan," said Shin Yul, a political science professor at Myongji University.

He said Seoul voters appeared to have been influenced in part by dissatisfaction with the government's housing policy, with authorities seeking to cool a hot market in the capital.

Still, the Democratic Party’s overall performance, including winning Busan - South Korea's second-largest city and a conservative stronghold - suggests Lee retains strong nationwide support, buo...