The ruling and opposition parties intensified their final appeals for support on the eve of the quadrennial parliamentary elections Tuesday, concentrating on the most fiercely contested battlegrounds in Seoul.

Wednesday's general elections are to pick 300 members of the National Assembly, with 254 of them to be selected through direct elections and the remaining 46 proportional representation seats to be allocated to parties according to the number of votes they receive overall.

The quadrennial race holds added importance for the ruling People Power Party as failure to regain a majority could potentially render President Yoon Suk Yeol a lame duck for the remaining three years of his single five-year term.

The main opposition Democratic Party aims to retain its parliamentary majority.

Han Dong-hoon, leader of the PPP, issued a desperate plea to the public early Tuesday before starting the final day of the 13-day official campaign period, imploring potential voters for support as the party needs a minimum number of seats to restrain the opposition bloc.

"Overwhelming support on Election Day is needed to prevent the Republic of Korea from falling into a state of decline," Han said.

He is scheduled to visit 14 competitive districts in the capital.

Han will then conclude his campaigning by joining other party members in central Seoul, alongside American Korean medical doctor Ihn Yohan, who previously served as the PPP innovation committee chief.

Observers view the 48 constituencies in Seoul as the primary battlegrounds that will ultimately determine the election outcome. Data suggests that the results in Seoul often mirror the overall election results.

Meanwhile, DP leader Lee Jae-myung is scheduled to focus his campaign efforts on key battlegrounds in the wider Seoul area, emphasizing the need to hold what the party deems as "the incompetent Yoon government" accountable for mismanaging the country.

Lee began the day with a visit to Incheon, west of Seoul, where he is running for a seat in the Gyeyang constituency.

The Gyeonggi and Incheon regions, which together have some 75 seats at stake, are considered a stronghold for the DP.

While on the campaign trail, Lee is also scheduled to attend a court hearing in Seoul over various corruption charges stemming from his tenure as the mayor of Seongnam, south of Seoul.

At the end of the day, Lee will join other party members for the last official campaign event at Yongsan Station in central Seoul, near the presidential office. (Yonhap)