Moon Jae-in, former head of the main opposition Democratic Party, and UN Secretary-General Ban Ki-moon are leading the way in approval rating for next year's presidential election, a pollster said Monday.

Moon stood in the No. 1 spot for the seventh consecutive week at 23.7 percent last week, up 0.6 percentage point from a week earlier, Real Meter said. The survey was conducted last week on 2,528 South Koreans with a margin of error of plus or minus 1.9 percentage points.

Ban followed with 20.5 percent, up 1.7 percentage points over the cited period. It marked the first time in seven weeks for the UN head to garner an approval rating beyond the 20 percent mark.

While the presidential election is slated for December next year, the race can be brought forward by a few months if South Korea's Constitutional Court gives the nod to the impeachment motion of President Park Geun-hye.

Park was impeached by the parliament earlier this month on alleged corruption and law-breaking activities.

Ban has not yet expressed his plan to join the race, although he also never denied such a possibility. Political pundits consider him as a likely candidate for the conservative bloc.

Seongnam Mayor Lee Jae-myung, which emerged as a key contender only recently, came in at the third spot at 14.9 percent, down 1.3 percentage points over the cited period. Following was Rep. Ahn Cheol-soo, former head of the People's Party, posting 8.3 percent.

Other candidates' approval ratings hovered below 5 percent, with conservative candidates Oh Se-hoon, former mayor of Seoul, and Rep. Yoo Seong-min only managing to post 2.9 percent and 2.2 percent, respectively.

By party, the Democratic Party posted an approval rating of 37.7 percent, marking the highest figure since the 41 percent posted by its predecessor in December 2012. The ruling Saenuri Party and People's Party posted 17.2 percent and 12.2 percent, respectively. (Yonhap)