Oh Se-hoon, center, the mayoral candidate of the main opposition People Power Party, holds flowers as he celebrates with party members after exit polls showed he would win.

Oh Se-hoon (C), mayoral candidate of the main opposition People Power Party, holds flowers as he celebrates with party members as they watch televisions broadcasting the results of exit polls for the Seoul mayoral by-election at the party’s headquarters in Seoul on April 7, 2021. (Photo by SONG Kyung-Seok / POOL / AFP) (Photo by SONG KYUNG-SEOK/POOL/AFP via Getty Images)