The final polls released before the public disclosure blackout for the June 3 local elections have made predicting the Seoul mayoral race even more difficult. Despite being conducted over similar periods using the same mobile telephone interview method, one survey showed a gap beyond the margin of error, while another revealed an extremely tight contest within the margin of error.
According to political circles on Wednesday, a Seoul mayoral poll commissioned by Donga Ilbo and conducted by Research & Research from Saturday to Monday surveyed 800 adults residing in Seoul via mobile telephone interviews. Jung Won-oh, the Democratic Party of Korea candidate, received 49.6%, leading People Power Party candidate Oh Se-hoon, who garnered 36.4%, by 13.2 percentage points — a margin outside the statistical error range. (Response rate: 9.8%; margin of error: ±3.5 percentage points at the 95% confidence level. For details, see the National Election Survey Deliberation Commission website.)
In this survey, Jung led Oh in all areas of Seoul except the southeastern region, which includes the three Gangnam districts (Gangnam, Seocho and Songpa), and the central district. In party support ratings, the Democratic Party also widely outpaced the People Power Party by 21.1 percentage points, with 47.0% versus 25.9%.
In contrast, a Munhwa Ilbo and Embrain Public survey released the same day (Monday to Tuesday, 805 Seoul adults via mobile telephone interview) showed Jung and Oh tied at 39%. (Response rate: 14.0%; margin of error: ±3.5 percentage points at the 95% confidence level.)
Throughout the election campaign, analysts have suggested that telephone interview polls tend to favor Jung, while mobile automated response system (ARS) surveys tend to favor Oh. Telephone interviews more easily capture responses from medium- and low-engagement voters rather than each candidate's most ardent supporters, which boosts Jung's numbers among those groups. ARS surveys, on the other hand, are seen as more accessible to "shy conservative" supporters, working to Oh's advantage.
However, the two polls released ahead of the disclosure blackout were conducted at nearly the same time using the same telephone interview method, making such comparisons difficult. Each candidate's camp is analyzing the polling results and seeking last-minute strategies to consolidate their support base.
"Regardless of the polling results, the Seoul election outcome will likely come down to a tight race within 5 percentage points," a political insider said. "The side that succeeds in seizing late-stage issues and rallying its supporters will have the advantage, and polling results should be used only as a reference."
