Early voting for South Korea's June 3 local elections and by-elections opened Friday across 3,571 stations nationwide. The vote is widely seen as a referendum on President Lee Jae Myung's first year.
The ruling Democratic Party and main opposition People Power Party stepped up efforts to mobilize supporters in tight races. The Seoul mayoral contest features a close matchup between incumbent Oh Se-hoon of the PPP and DP candidate Chong Won-o.
A National Election Commission poll showed 39.3 percent of voters plan to use early voting, citing convenience as the top reason. Turnout has risen steadily since early voting began in 2014.
Races are also tightening in Daegu, Busan and Ulsan. Former PPP leader Han Dong-hoon is running as an independent in the Busan Buk-A by-election.