When the final results of today's by-election are in, they could very well show a split down party lines.
According to analysis conducted by the rival parties, each side is expected to win in three to four constituencies, while it's anybody's guess who will take the remaining electoral districts.
The ruling party and main opposition party have taken different approaches to appeal to voters.
The conservative party has been touting its connection to President Park Geun-hye, with candidates pledging economic stimulus packages for their districts.
The main opposition New Politics Alliance for Democracy has taken aim at the incumbent government,. asking voters to hold the ruling party responsible for its perceived poor handling of April's ferry disaster and the ensuing investigation.
To win in the most politically important regions, both parties have brought out their big guns.
Former opposition leader Sohn Hak-kyu is not only hoping to win a seat in the city of Suwon; he's hoping to solidify his position within the opposition bloc.
The ruling party's Lee Jung-hyun, a former presidential secretary and key ally of President Park Geun-hye, has taken on the challenge of competing in Jeollanam-do province, a traditional liberal stronghold.
A win from Lee would represent a heavy blow to the opposition bloc.
Ji Myung-kil, Arirang News.