President Yoon Suk Yeol's approval rating fell below 40 percent for the first time in five weeks in the wake of hard-line remarks he made on North Korea and a row with a potential candidate to become leader of the ruling People Power Party, a poll showed Monday.

In the poll of 2,508 adults conducted by Realmeter from Monday to Friday of last week, 39.3 percent positively assessed Yoon's performance, down 1.6 percentage points from the previous week.

Yoon's disapproval rating was 58.4 percent, up 2.5 percentage points over the same period.

This marks the first time in five weeks Yoon's approval rating has sunk below the 40 percent mark since the second week of December.

The fall was attributable to a series of hawkish remarks Yoon made on North Korea as well as a row with Na Kyung-won, a former four-term PPP lawmaker considered a leading potential contender for PPP leader, according to Bae Cheol-ho, a senior analyst at Realmeter.

Na offered to resign as vice chair of the presidential committee on low birthrates after her policy suggestion ran afoul of the presidential office, and Yoon later fired her not only from the position, but also as ambassador for climate and environment.

Yoon's move was widely seen as an expression of displeasure with Na potentially running for PPP leader.

On the favorability rating of political parties, Yoon's PPP garnered 40.5 percent support, while the main opposition Democratic Party registered 45.7 percent.

The poll has a margin of error of plus or minus 2 percentage points at a 95 percent confidence level. (Yonhap)