President Moon Jae-in’s Democratic Party was handed its worst defeat in five years in mayoral elections in South Korea’s two biggest cities, a troubling sign for his progressive bloc just 11 months before a presidential vote.

Final results released Thursday showed conservative Oh Se-hoon scored a landslide victory in the race in Seoul over ruling party candidate Park Young-sun, a former minister for startups. Oh picked up 57.5% of the vote to 39.2% for Park. In Busan, Park Hyung-jun of the conservative People Power Party defeated Kim Young-choon from Moon’s ruling party by 62.7% to 34.4%, data from the National Election Commission showed.

A key issue in the races was anger over housing prices in major metropolitan areas that have soared under Moon. The losses in the cities that account for about a quarter of South Korea’s population could slam the brakes on Moon’s agenda to increase public employment and a push for larger fiscal spending. The setbacks could also serve as warning to his Democratic Party that it needs to revamp its policies if it wants to keep the presidency when Moon’s single, five-year term ends in 2022.