Residents in South Korea's two main cities are voting in mayoral elections that are widely seen as an important precursor to the presidential election to be held next March.
Voting of the by-elections began at 6 a.m. on Wednesday in the capital, Seoul, and the second-largest city of Busan.
In Seoul, the ruling Democratic Party has fielded former cabinet minister Park Young-sun. Park is facing off against the largest opposition People Power Party's candidate and former Seoul mayor Oh Se-hoon.
Contenders from the two parties are also running in Busan.
Polling stations will close at 8 p.m. People who are quarantined for anti-coronavirus measures will cast their ballots after the closure.
The elections are held as the approval ratings for President Moon Jae-in fall to record lows due partly to alleged illegal land transactions by public officials amid soaring real estate prices.
South Korean media are reporting that the setback may affect the outcome of the elections.