South Korean voters on Wednesday went to polls to cast ballots for new mayors in Seoul and Busan, the country's two biggest cities.
Polling started at 6 a.m. local time (2100 GMT a day earlier) at 3,459 polling stations across the country and will last till 8 p.m. (1100GMT), according to Yonhap News Agency.
In Seoul, 8.4 million voters are eligible to vote, while Busan has slightly more than 2.9 million qualified voters.
Park Won-soon in Seoul and Oh Keo-don in Busan left their mayoral posts last year amid sexual harassment allegations. Park was found dead last July, while Oh stepped down in April.
The new mayors will serve the remaining 14 months of the former mayors' four-year terms.
The by-elections are seen as a test case for the ruling party ahead of the presidential race set for March 2022.
The president and the ruling Democratic Party have been grappling with public outrage and falling public support ratings over spiking housing prices, deepening inequality and souring ties with North Korea.