Democratic Party of Korea candidate Ha Jung-woo campaigns in Busan on Tuesday ahead of the National Assembly by-election in Busan's Buk-A district. (Yonhap) Democratic Party of Korea candidate Ha Jung-woo and independent candidate Han Dong-hoon were locked in a tight race in the National Assembly by-election for Busan's Buk-A district, according to a joint exit poll released Wednesday after voting ended.The exit poll showed Ha with 42.6 percent support, narrowly ahead of independent candidate Han Dong-hoon at 41.6 percent. People Power Party candidate Park Min-sik garnered 15.8 percent.The exit poll covered 595 polling stations nationwide Wednesday and was supplemented by telephone surveys of 28,500 respondents. It was conducted by the Korea Election Pool, a body comprising representatives of the Korean Broadcasters Association and broadcasters KBS, MBC and SBS.The race drew national attention as it pitted Ha against Han, a former leader of the People Power Party who ran as an independent candidate.Ha, a former presidential secretary for artificial intelligence under President Lee Jae Myung and a former Naver executive, was nominated by the Democratic Party for the constituency previously held by the party.Han emerged as one of the leading conservative figures during the administration of former President Yoon Suk Yeol and later served as leader of the People Power Party.Han gradually distanced himself from Yoon and the pro-Yoon faction during his tenure as party leader, with the relationship effectively breaking down following the former president's Dec. 3, 2024, martial law declaration.A victory for Ha would help the ruling party defend one of the most closely watched constituencies contested in the by-elections held alongside South Korea's local elections.A victory for Han would mark his first entry into the National Assembly and strengthen his standing among conservatives seeking a clearer break from Yoon.