Moon Jae In, the front-runner in South Korea's presidential race, has widened his lead over second-place Ahn Cheol Soo ahead of the May 9 presidential election, according to an opinion poll released by Gallup Korea on Friday.

Moon, of the Democratic Party of Korea, which holds the most seats in parliament, received 41 percent support, up 1 percentage point from last week, while Ahn of the People's Party, the country's third-largest party, saw his approval rating plummet 7 points to 30 percent.

"It appears some of Ahn's supporters have reversed their stance in the wake of the vetting process and negative campaigns that have been intensified after official campaigning started" on Monday, according to the pollster.

In recent opinion polls, Ahn, a 55-year-old former medical doctor and antivirus software developer, has emerged as a major contender to Moon, a 64-year-old former human rights lawyer and close aide to former President Roh Moo Hyun.

Hong Joon Pyo of the conservative Liberty Korea Party, Sim Sang Jeung of the progressive Justice Party and Yoo Seong Min of the splinter conservative Bareun Party were trailing far behind in the poll.

The presidential election is heavily tilted toward candidates from liberal parties in the wake of the corruption and abuse-of-power scandal that brought down President Park Geun Hye.

Park, impeached by parliament in December and put behind bars late last month, stands accused of letting her now-jailed confidante Choi Soon Sil, a private citizen, meddle in state affairs while colluding to extort donations from businesses for two foundations under Choi's effective control. She had one year left in her five-year term when ousted from office in March.

The poll was conducted Tuesday through Thursday on 1,004 voters nationwide.

South Korea's presidential race is taking place amid rising tensions, as North Korea continues to defy U.N. resolutions with ballistic missile launches and is showing signs of possibly conducting what would be its sixth nuclear test.

==Kyodo