An election official checks posters of candidates running in the June 3 local elections at an election management committee office in Seoul on Wednesday. (Yonhap) Official campaigning for the June 3 local elections and parliamentary by-elections kicked off Thursday, with the ruling and opposition parties launching all-out efforts to sway voters.The 13-day campaign period will run through the eve of the elections, during which candidates and their campaign teams will be allowed to give speeches in public places between 7 a.m. and 11 p.m., distribute campaign materials and put up campaign banners.This year's elections have drawn greater attention as 14 National Assembly seats are also at stake in parliamentary by-elections, 13 of which were previously held by the ruling Democratic Party.Han Dong-hoon, former chief of the main opposition People Power Party, is running as an independent for his National Assembly seat in the parliamentary by-elections in Busan's Buk-A constituency. He is running against Ha Jung-woo of the DP, former presidential secretary for artificial intelligence policy and future planning, and former PPP lawmaker Park Min-shik.While Busan is a traditional conservative stronghold, the Buk-A constituency is the only district among the city's 18 constituencies won by the DP in the last parliamentary elections, making the race a key battleground for both the liberal and conservative camps.Other notable contests include the race in Pyeongtaek-B constituency, where Cho Kuk, leader of the liberal Rebuilding Korea Party, is facing Kim Yong-nam of the DP and Yu Eui-dong of the PPP, as well as former Prime Minister Hwang Kyo-ahn of the minor Freedom and Innovation Party, and Kim Jae-yeon of the minor progressive Jinbo Party.Also closely watched is the mayoral election in Seoul, where incumbent Mayor Oh Se-hoon of the PPP and the DP's Chong Won-o are locked in a tightening race.Next month's elections are widely considered the first major nationwide test for the Lee Jae Myung administration since it took office last June following former President Yoon Suk Yeol's ouster over his failed martial law bid.The DP, which currently controls a majority in the National Assembly, is seeking to clinch victories on the back of Lee's high approval ratings.The PPP aims to rally support from conservative voters to rebuild the conservative bloc amid deepening internal rifts in the aftermath of Yoon's martial law bid.A total of 7,829 candidates have registered for the elections, including 54 candidates vying for 16 metropolitan mayors and provincial governors, and 585 candidates for 227 heads of lower-level administrative units in the upcoming elections.Early voting is set to be held for two days from next Friday. (Yonhap)