Ahn Cheol-soo, the presidential candidate of the minor opposition People's Party, came out on top in a poll released Sunday in a hypothetical alliance with the major opposition nominee Yoon Suk-yeol.

In a survey by Southern Post, Ahn earned 42.3 percent of support as the main opposition candidate in case of a unified presidential bid with Yoon, the People Power Party (PPP) nominee. Lee Jae-myung, representing the ruling Democratic Party, had 28.9 percent support in that scenario.

The survey was conducted on 1,002 people from Friday to Saturday. It had a margin of error of plus or minus 3.1 percentage points.

In the same poll, 34.4 percent said they would support Yoon if he ended up as the standard-bearer of the opposition in an alliance with Ahn. Lee had 33.6 percent support in that hypothetical situation.

In a multicandidate race without any alliance for the opposition, Lee led the poll with 34.1 percent, followed by Yoon at 26.4 percent. Ahn garnered 12.8 percent support, more than double the figure from the previous poll by Southern Post conducted from Dec. 29-30.

Of Yoon supporters in the multicandidate battle, 69.3 percent supported Ahn in case of an Ahn-led alliance. And 11.6 percent of Lee supporters switched allegiance to Ahn.

But only 30.6 percent of Ahn backers in the multicandidate race said they would support Yoon if Yoon became the unified opposition candidate.

Southern Post said 44.3 percent of the respondents supported the unification of opposition candidates, while 37.8 percent said they were against the idea and 18 percent said they either didn't know or didn't respond to the question.

Yoon has seen his support ratings plummet in recent surveys, with the PPP reeling from internal feuds that led to mass resignations of senior campaign officials at the start of the new year.

Ahn has repeatedly said he is in the race to win the election on his own power, though the founder of the nation's biggest anti-virus software company AhnLab has a track record of pulling out of races.

In 2011, Ahn considered running in a by-election for the Seoul mayoralty with his support ratings exceeding 50 percent. But he quit the race, lending his support to candidate Park Won-soon who won the election.

Ahn emerged as a dark horse during the 2012 presidential campaign, but dropped out at the last moment to help boost the chances of then main opposition candidate Moon Jae-in.

Moon was defeated by then ruling party candidate Park Geun-hye in the race. Moon won the presidential election in 2017 and he is barred from seeking re-election by law.

South Koreans will go to polling stations on March 9 to elect a new president. (Yonhap)