Main opposition presidential candidate Yoon Suk-yeol leads his ruling party rival Lee Jae-myung in a hypothetical two-way race, according to polls conducted before Yoon merged candidacies with Ahn Cheol-soo of the minor People's Party.

According to a survey conducted by Embrain Public from Tuesday to Wednesday, Yoon led Lee 45.9 percent to 45 percent in a hypothetical two-way race. The gap of 0.9 percentage point was within the margin of error of plus or minus 3.1 percent at a 95 percent confidence level.

Another survey conducted by Embrain Public from Monday to Wednesday, Yoon led Lee 47.4 percent to 41.5 percent in a hypothetical two-way race. The 5.9-percentage point gap points was outside the margin of error of plus or minus 2.2 percentage points at a 95 percent confidence level.

Earlier in the day, Ahn dropped out of the race and declared his support for Yoon.

The merger could boost Yoon's chances in the tight race where he and Lee of the ruling Democratic Party have been running neck and neck with around 40 percent support each in recent polls, while Ahn has had around 10 percent.

By law, polls conducted within six days of the election cannot be published until after voting closes, but polls conducted before the restriction can be published. (Yonhap)

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