A lawmaker of the People Power Party (PPP) offered Sunday to leave the main opposition party amid mounting criticism over his son receiving a massive severance pay from a firm at the center of a controversial land development scandal.

Rep. Kwak Sang-do submitted to a regional party chapter a document to end membership with the party, Rep. Kim Gi-hyeon, the party's floor leader, said, as his political opponents ramped up an offensive against Kwak over the severance pay.

His son reportedly received 5 billion won ($4.24 million) after some seven years of work at Hwacheon Daeyu Asset Management, suspected of reaping huge gains from the land development project in Seongnam launched in 2015 when Gyeonggi Gov. Lee Jae-myung, currently a presidential front-runner for the ruling Democratic Party, was the city's major.

"Whether Kwak has any legal responsibility to take or not will be revealed during an investigation process later, but regardless of that, the People Power Party feels a heavy sense of responsibility regarding political accountability as a public figure," Kim, the floor leader, said.

Kwak has been striving to shake off the criticism over the severance pay issue, stressing the fundamental responsibility lies on Gov. Lee, whose municipality then allowed the development project to go ahead.

His offer to quit the party came amid concerns growing criticism over his son's severance pay could become a liability as the party is quickening preparations for the March 9 presidential election. (Yonhap)