SEOUL - A month before South Koreans choose a new president, the once-narrow gap between the two main candidates is widening.

At least two polls conducted over the Chinese New Year holidays put the main opposition candidate Yoon Suk-yeol ahead of his biggest rival, Mr Lee Jae-myung from the ruling Democratic Party, who has taken a beating due to a power abuse scandal involving his wife.

A study released on Friday (Feb 4) by Research View put Mr Yoon's approval rating at 46 per cent to Mr Lee's 38 per cent.

Another survey by Korea Social Opinion Research Institute cited a 45.7 per cent support rate for Mr Yoon, as opposed to Mr Lee's 40 per cent.

The two front runners have been locked in a neck and neck race since last November with their parties often resorting to mudslinging attacks, harping on scandals and internal feuds more than dissecting the promises and policies of the opposing candidate.

Experts noted that Mr Yoon, a 61-year-old former prosecutor-general with no experience in politics, has managed to settle the feuds within his party - the conservative People Power Party (PPP) - and won the support of its young leader Lee Jun-seok, 36.

Political commentator David Lee said Mr Yoon's support rate is highest among conservative supporters, who tend to be aged above 60, and young voters in their 20s, who are easily swayed, including by two recent controversies involving the wives of the two main candidates.

One was about leaked recordings of conversations between Mr Yoon's wife and a journalist.

"Older age groups were shocked by hints that Yoon and his wife consulted shamans for advice and how she had a hand in his campaign strategy," said Mr Lee.

"But younger age groups were taken in with how his wife spoke, not the typical demure partner but someone assertive with her own mind. On the other hand, Lee's wife is embroiled in a gapjil scandal which young people hate, so that would have affected the poll results."

Gapjil, which refers to how people in positions of power abuse those weaker than them, has been deemed to be a serious problem in South Korea.

The wife of Mr Lee Jae-myung, 57, a former governor of Gyeonggi province, was recently accused of using a government-issued credit card for personal purchases and ordering provincial officials to run personal errands for her, such as buying groceries as well as medical prescriptions, last year.

The couple have denied the allegations but still apologised for failing to draw a clear line between public and private matters.

Surprisingly though, the so-called "wife risk" topic did not come up when Mr Lee and Mr Yoon crossed swords live on television on Thursday (Feb 3) night, during a presidential debate that also involved the two other minor candidates - Mr Ahn Cheol-soo of the People's Party and Ms Sim Sang-jung of the Justice Party.

Instead, the four candidates traded barbs for over two hours on issues that mattered, ranging from real estate policy to renewable energy and aid for those hard hit by the Covid-19 pandemic. They also sparred over North Korea and United States-China rivalry.

A ritual since 1997 and inspired by those held in the US, Thursday's television debate scored 39 per cent in viewership - much higher than the 22.1 per cent for the previous one held in 2017.

A recent poll showed that one in four respondents may decide on their vote depending on the results of the debate.

Real estate policies took centre stage in the beginning on Thursday, as both candidates discussed ways to address skyrocketing property prices that the current Moon Jae-in administration has failed to curb.

Mr Yoon also tried to demand an explanation from Mr Lee about a corruption scandal linked to a housing project in Seongnam city, which the latter oversaw during his term as the city's mayor. But Mr Lee insisted he had nothing to do with the issue which is now being investigated by the authorities.

The candidates also discussed foreign policy issues.

Ms Sim accused Mr Yoon of warmongering for suggesting pre-emptive strikes on North Korea, but he argued that they may be necessary to prevent war.

Mr Lee criticised Mr Yoon's recent remarks that South Korea should deploy another anti-missile defence system - a move that would anger China and possibly trigger economic retaliation, as it did in 2017 when the first such system was deployed.

"He should not exploit the public's anti-China sentiments for votes," said Mr Lee.