The two-day candidate registration period for the June 1 local and parliamentary by-elections are set to end later on Friday.

In Seoul, incumbent Mayor Oh Se-hoon of the ruling People Power Party(PPP) will seek another term, squaring off against the former chairman of the main opposition Democratic Party(DP), Song Young-gil.

In Gyeonggi Province, a highly contested region, it's expected to be a neck and neck race for the governorship between the PPP's Kim Eun-hye and the DP's Kim Dong-yeon.

Among seven parliamentary constituencies set to be filled during the by-elections, former DP presidential candidate Lee Jae-myung is seeking to enter parliament for the first time through a by-election in Incheon's Gyeyang-B District.

Former People's Party presidential candidate Ahn Cheol-soo, now a member of the PPP, is vying for a seat representing Seongnam's Bundang-A District.

The official 13-day campaign period will start May 19 and run through 31. Early voting will be held between May 27 and 28.