Who's who in key election battlegrounds?

With 4,241 posts up for grabs in Wednesday's elections, including 16 key executive seats and 14 parliamentary seats being contended in by-elections, several races stand out as key battles.

The outcomes could have significant ramifications for either of the two main parties, as well as the Lee Jae Myung administration itself.

Chong Won-o, the Democratic Party of Korea's Seoul mayoral candidate, has consistently been ahead in opinion polls, but his lead over incumbent Seoul Mayor Oh Se-hoon has been narrowing.

Chong served for 12 years as the chief of the Seongdong-gu District Office, the jurisdiction of which covers Seongsu-dong, whose old brick architecture preserved alongside hip refurbishments have given it the nickname of "Seoul's Brooklyn."

Chong quickly stepped into the media limelight after President Lee Jae Myung posted an X post in December that recognized Chong as a figure who "must be good at his job" as the district office chief.

Backed by Lee's de facto endorsement, Chong clinched victory in the party primary, however, he has been embroiled in controversies including over violent behavior in 1995 and a business trip to Cancun, Mexico, in 2023.

Oh, affiliated with the conservative People Power Party, has been under fire for his launch of the Hangang Bus, a river bus network on the Han River, as it has suffered malfunctions and shutdowns multiple times.

Recent findings concerning alleged construction glitches with the GTX-A commuter rail project in Gangnam-gu, Seoul, as well as the deadly collapse of the closed Seosomun Overpass while work was underway to demolish it, have meanwhile left Oh — seeking a fifth term as Seoul mayor for the first time in South Korea's history — vulnerable to attack.

Chun Jae-soo was the only left of center lawmaker to have been elected across all of the 18 constituencies in Busan in the 2024 general election.

Standing out in the conservative stronghold, which is South Korea's second-most populous city, Chun was appointed to become the first oceans minister in the Lee Jae Myung administration last year.

He spearheaded the move to relocate the headquarters of the Oceans Ministry to Busan, in line with the Lee administration's efforts to balance economic growth and turn Busan into an international maritime hub.

Now, Chun is contending for the Busan mayoral seat, facing off against incumbent conservative Busan Mayor Park Heong-joon, who is seeking a third term.

Kim Boo-kyum, the Democratic Party's candidate for Daegu mayor, will walk an unprecedented path if he is elected in the conservative stronghold.

Daegu has never elected a liberal mayor since South Korea introduced local elections in 1995. But Kim, a former prime minister and four-term lawmaker, might be the closest that any liberal candidate has gotten to blazing that trail.

He was already the first lawmaker in more than three decades to be elected in Daegu on a center-left party's ticket. Kim served in the constituency of Suseong-A from 2016 to 2020, his fourth term as a seasoned lawmaker.

Kim was also the runner-up in the 2014 Daegu mayoral election, but earned over 40 percent of the vote.

Polls showed that Kim is now in a neck-and-neck race against Choo Kyung-ho, a former three-term lawmaker and floor leader of the People Power Party.

However, support for Choo appears to have recently been buoyed by former President Park Geun-hye's public appearance on his campaign trail.

Until a few months ago, few imagined that the Democratic Party would lose the governorship of one of its biggest strongholds.

That was until Kim Kwan-young, the incumbent governor of North Jeolla Province, was expelled from the ruling party during the candidate nomination process.

Leaked footage suggested that Kim had been distributing cash envelopes to young party members and councilors in a restaurant. His supporters have posited that rival candidate Lee Won-taeg had also been embroiled in a similar scandal, but the party went on to nominate him anyway.

Recent opinion polls have put party exile Kim, who is now running as an independent, ahead of Lee.

Cho Kuk, a close aide to former President Moon Jae-in, is seeking a dramatic comeback to the National Assembly in a by-election in Pyeongtaek, Gyeonggi Province.

A longtime aide of the former president and advocate for prosecutorial reform, Cho fell from grace after an academic credentials forgery scandal involving his family drew public backlash in 2019.

Cho returned to politics in May 2024 when he was elected as the lawmaker of the minor liberal party he founded, the Rebuilding Korea Party. However, his conviction at the top court in December the same year forced him to leave the National Assembly. A pardon by the Lee administration the following August cleared him to take public office again.

Cho is seeking redemption as the Rebuilding Korea Party candidate for a parliamentary seat in the Pyeongtaek-B electoral district.

Cho will have to overcome a crowded field. His ruling party opponent is Kim Yong-nam, a former lawmaker aligned with conservative parties until last year. Also on the ballot are People Power Party candidate Yu Eui-dong, who is a former lawmaker who represented the district, minor Progressive Party leader Kim Jae-yeon and Hwang Kyo-ahn, a former prime minister and prominent hard-right figure.

In another party stronghold, another ousted member could steal the limelight, this time from the conservatives.

Han Dong-hoon, an independent candidate in Busan's Buk-A legislative by-election, is ahead in the polls on the home turf of the People Power Party he once led.

Han, a longtime ally of former President Yoon Suk-yeol, previously served as the chair of the People Power Party and led the right-wing party in the 2024 general election campaign.

Han stepped down from the chair position soon after a motion to impeach Yoon in the wake of the December 2024 martial law crisis passed the National Assembly, with some lawmakers in his camp voting in favor.

Just over a year later in January, Han was expelled from the party he had chaired over internal criticism of Yoon.

Han is squaring off against the Democratic Party's Ha Jung-woo, who recently stepped down as senior presidential secretary for artificial intelligence and future planning, and the People Power Party's Park Min-shik, a former veterans affairs minister.