Rival parties are battling it out at the last minute for the two most contested constituencies in Wednesday’s by-election: Busan’s Geumjeong District and Yeonggwang County, South Jeolla Province. 

Though it has been called a "mini by-election," it is considered a crucial step in gauging public sentiment since the general election in April, and both the ruling and opposition parties are giving the campaign their all until midnight Tuesday.

The election is also the first to be held under the leadership of ruling People Power Party leader Han Dong-hoon and main opposition Democratic Party leader Lee Jae-myung. 

Shin Ji-ho, the head of the ruling party’s strategic planning department, told KBS Radio that Han’s leadership will face problems both inside and outside the party should it lose in Geumjeong or in Ganghwa County, Incheon. 

He said if the party wins in both regions, the groundwork will be in place for Han to take the next step as its leader. 

A Democratic Party official, meanwhile, told KBS that the party will exert all-out efforts to win in Geumjeong, saying dissatisfaction is growing in the district toward the Yoon Suk Yeol government amid various suspicions surrounding the first lady.