Moon Jae-in, a former leader of the main opposition Democratic Party, maintained a substantial lead in two-way hypothetical races with all potential rivals for the presidency, a survey showed Monday.

After former UN Secretary-General Ban Ki-moon renounced his presidential ambitions on Wednesday, Moon's front-runner position appears to have been bolstered with South Chungcheong Governor An Hee-jung and Acting President and Prime Minister Hwang Kyo-ahn quickly rising in popularity.

The survey -- commissioned by Yonhap News Agency and KBS, and conducted on Sunday and Monday by Korea Research Center -- found that Moon ranked first with 29.8 percent support, a gain of 8.2 percentage points from the previous survey released on Jan. 1.

Moon was trailed by An with 14.2 percent, up 9.6 percentage points from the pollster's previous survey, and the acting president with 11.2 percent, up 7.8 percentage points.

Ahn Cheol-soo, a former leader of the liberal People's Party, and Seongnam Mayor Lee Jae-myung were tied at 6.3 percent.

Rep. Yoo Seong-min of the minor conservative Bareun Party ranked sixth with an approval rating of 3.2 percent, followed by former Democratic Party chief Sohn Hak-kyu with 1.1 percent and Rhee In-je of the ruling Saenuri Party with 0.7 percent.

In a two-way race, Moon garnered a support of 52.3 percent, more than double the acting president's rating that stood at 23.6 percent. In separate competitions against Yoo and Ahn, Moon also maintained a comfortable double-digit lead.

In three-way races, Moon was way ahead of all other contenders as well.

In a race involving Hwang and Ahn, Moon gained 45 percent while the pair posted 20.5 percent and 15.1 percent, respectively. In a contest that pitted him against Ahn and Yoo, Moon's rating came to

43.5 percent while the other two hopefuls took 16.3 percent and 14.6 percent, respectively.

Among the respondents who supported former U.N. chief Ban, 36.6 percent questioned said they would vote for the acting president, while 10.6 percent said they will consider supporting the South Chungcheong governor.

What was notable in the latest survey was the declining support for Lee Jae-myung, a vocal critic of impeached President Park Geun-hye who was seen as a up-and-coming opposition contender in the previous poll. His rating, which stood at 11.4 percent, nearly halved.

By party, the Democratic Party ranked first with 43 percent support, up 6.7 percentage points from the previous survey, followed by the Saenuri Party with 12.5 percent, the People's Party with 8.9 percent and the Bareun Party trailing at 7.0 percent.

The survey was conducted on 2,016 South Korean voters across the country. Its margin of error is plus or minus 2.2 percentage points. (Yonhap)