Ruling party presidential candidate Lee Jae-myung is running neck and neck with his main opposition rival, Yoon Suk-yeol, at 40.4 percent support against Yoon's 38.5 percent, a poll showed Thursday.

Lee of the liberal Democratic Party gained 5.1 percentage points from the pollster's previous survey on Jan. 8-10, and Yoon of the conservative People Power Party edged up 0.5 point, according to the survey of 1,012 adults conducted by Hangil Research on Wednesday.

The gap between Lee and Yoon was within the margin of error of plus or minus 3.1 percentage points. Ahn Cheol-soo, the presidential candidate of the minor opposition People's Party, came in third with 8.2 percent, while Sim Sang-jeung of the minor progressive Justice Party followed at 3.3 percent.

By age group, Lee was popular among voters in their 30s, 40s and 50s, earning 43.1 percent, 50.5 percent and 49.3 percent, respectively.

Yoon performed well among voters in their 20s and 60s, scoring 37.2 percent and 50.9 percent, respectively. (Yonhap)

For more information regarding the survey results, visit the National Election Survey Deliberation Commission homepage.