President Yoon Suk-yeol's approval rating sank below 30 percent in the wake of the embarrassing disclosure of a controversial text conversation with the ruling party floor leader, a poll showed Monday.

In the poll of 1,003 voters nationwide conducted by pollster Korea Society Opinion Institute (KSOI), 28.9 percent said Yoon was doing well on state affairs, down 3.3 percentage points from the previous week, while those who gave a negative assessment rose 4 percentage points from a week ago to 68.5 percent.

The result came amid leadership turmoil at the ruling People Power Party.

Last week, PPP floor leader Kweon Seong-dong apologized after a text conversation he had with Yoon was caught on camera, in which Yoon was seen backbiting about suspended party chief Lee Jun-seok.

Kweon took over as acting leader of the party in early July after the party's ethics committee suspended Lee's party membership for six months over allegations of sexual bribery and a cover-up.

On Sunday, Kweon offered to resign. The incident also prompted three members of the party's Supreme Council to quit amid speculation the party could switch to a collective leadership system from its one-man leadership.

On views that Yoon's opinion could have affected the disciplinary measure against Lee, the KSOI poll showed that 68.8 percent agreed with the claim, while 25.5 percent dismissed it.

In a separate poll of 2,519 voters nationwide conducted by pollster Realmeter between Monday and Friday, 33.1 percent said Yoon was doing well on state affairs, down 0.2 percentage point from the previous week.

Those who gave a negative assessment rose 1.1 percentage points from a week ago to 64.5 percent.

A daily breakdown of the poll showed that Yoon's approval rating fell sharply from 38.3 percent on Tuesday to 28.7 percent on Friday. The pollster said it was its first survey in which Yoon's approval rating fell below 30 percent on a daily basis.

The KSOI poll had a margin of error of plus or minus 3.1 percentage points at a 95 percent confidence level. The Realmeter survey had a margin of error of plus or minus 2 percentage points at a 95 percent confidence level. (Yonhap)