Moon Jae-in, a presidential candidate of South Korea's biggest Minjoo Party, kept his top spot in recent opinion polls for 15 straight weeks, with less than a month left before the presidential election.
According to a Realmeter survey released on Thursday, Moon garnered 44.8 percent of support this week, up 2.6 percentage points from the previous week.
It was based on a poll of 1,525 voters conducted between Monday and Wednesday. It had 2.5 percentage points in margin of error.
Moon ranked first in opinion surveys for the 15th consecutive week. He gained the biggest support in all regions except North Gyeongsang province, the traditional support base for conservative politicians.
An early presidential election is scheduled for May 9 as former President Park Geun-hye was impeached on March 10 and arrested three weeks later over a corruption scandal.
Moon was followed by Ahn Cheol-soo of the People's Party, which splintered away from the Minjoo Party in early 2016. Ahn's approval rating rose 2.4 percentage points from the previous week to 36.5 percent this week.
Ahn was supported especially by conservative voters aged 50 or more, while Moon's support base was liberal and centrist voters aged below 50.
Hong Joon-pyo of the former ruling Liberty Korea Party, won 8.1 percent of support, trailed by Sim Sang-jung of the progressive Justice Party with 2.8 percent and Yoo Seong-min of the conservative Righteous Party with 1.7 percent.
In a simulated three-way race between Moon, Ahn and Hong, Moon gained 47.0 percent of support, followed by Ahn with 37.2 percent and Hong with 8.8 percent.
In a showdown simulation between Moon and Ahn, the former beat the latter by 49.0 percent to 41.1 percent.
Support for the Minjoo Party gained 1.6 percentage points from the previous week to 44.8 percent this week. The People's Party ranked second with 26.5 percent in support scores, up 3.3 percentage points from a week earlier.
It was followed by the Liberty Korea Party with 9.0 percent, the Justice Party with 5.1 percent and the Righteous Party with 3.7 percent.
