South Koreans will elect a new head of state on May 9, but Acting President Hwang Kyo Ahn, the ruling party's top candidate in opinion polls, has announced that he will not run, leaving the embattled Liberty Korea Party in a spot and boosting the opposition's chances.
At a Cabinet meeting yesterday, Mr Hwang said: "After careful consideration of the current national crisis and in order to stabilise state affairs and manage fair elections, I have come to the conclusion that it is not appropriate for me to run in the presidential election."
The polling date was also announced during the Cabinet meeting - five days after former president Park Geun Hye's impeachment.
She is facing a criminal probe over her role in a corruption and power abuse scandal.
Prosecutors are set to question Ms Park next Tuesday. Her lawyer said in a text message to reporters that she will "sincerely accept" the investigation.
The opposition camp's presidential hopefuls welcomed Mr Hwang's decision yesterday. Mr Ahn Cheol Soo from the minor People's Party urged him to focus on leading the country now.
But Mr Hwang's withdrawal leaves the ruling party with no strong candidate.
The party is also struggling with an approval rating of only 9 per cent and faces an imminent exodus of anti-Park members to the splinter Bareun Party.
Even though Liberty Korea Party has 10 presidential hopefuls, including North Gyeongsang Governor Kim Kwan Yong and South Gyeongsang Governor Hong Jun Pyo, Yonsei University political science professor Rhyu Sang Young said none of them has an approval rating of more than 1 per cent in opinion polls.
"The opposition has a good chance to win the election," he said. "The ruling party will try to make some moves to raise its popularity, but it is very hard when none of their candidates stands out."
Opposition parties have sped up their election preparations. The main Democratic Party's four contenders - former party chairman Moon Jae In, who is leading in polls with an approval rating of more than 36 per cent; South Chung- cheong Governor An Hee Jung; Seongnam Mayor Lee Jae Myung; and Goyang Mayor Choi Sung - meet next Tuesday to declare a fair primary race.
For smaller parties, including the People's Party and Bareun Party, there is now talk of a possible merger to run a stronger campaign against Mr Moon.
Analysts said presidential candidates will have a hard time addressing critical challenges such as a slowing economy, political reform, a belligerent North Korea and worsening ties with China and Japan.
Professor Rhyu noted that calls to revoke bilateral agreements made by the Park administration have grown and presidential candidates "cannot disregard the voice of the people against these issues".