Seoul, Feb 17 : Yoon Suk-yeol, South Korea's main opposition's presidential candidate, is leading his ruling party rival Lee Jae-myung with 40 per cent public support against the latter's 31 per cent, a survey showed on Thursday. Yoon of the conservative People Power Party gained 5 percentage points from last week, while Lee of the liberal Democratic Party lost 4 percentage points, according to the poll conducted on 1,012 adults from Monday to Wednesday by Embrain Public, Kstat Research, Korea Research and Hankook Research. The gap between Yoon and Lee was outside the margin of error of plus or minus 3.1 percentage points at a 95 per cent confidence level, reports Yonhap News Agency. Ahn Cheol-soo of the minor opposition People's Party garnered 8 per cent support, down 1 percentage point from last week. Sim Sang-jeung of the minor progressive Justice Party lost 2 percentage points to post 2 per cent. When asked to pick the candidate most likely to win, 48 per cent of the respondents chose Yoon, while 32 per cent opted for Lee. The survey also found 50 per cent said an opposition candidate must win the March 9 election, while 38 per cent said a ruling party candidate should win the election. /IANS