The move could lead ultimately to Hong's fall, and may in turn force top GNP presidential contender Park Geun-hye to return to the party's front line for the first time in years. There have been calls from within the party that Park should take over and rebuild the party.

Hong, however, refused to step down, saying he will act in a "responsible" manner.

During a hastily arranged press conference, Hong also said he has a "roadmap" to "recreate" the party in a way that will regain public confidence, but did not elaborate on the plan, saying it was not the right time to disclose it.

Hong also said he won't try to cling to his post, suggesting he could resign after overseeing the passage of next year's budget bill through parliament and putting together a set of measures to revamp the party.

The three lawmakers were among the five members of the GNP's Supreme Council led by Hong.

Yoo told a press conference that he decided to quit the council to "take responsibility for failing to salvage the party from a crisis of life or death," and offered an apology to the people over what he called "people's despair and anger" toward his party.

Won went further, calling for "thoroughly" breaking up the GNP as repentance to the people and creating a "healthy and reformist conservative party." Won, a three-term lawmaker considered a leader of reformist members, said he would stage a campaign for the cause.

Nam told a party meeting that all party leaders should resign en masse, sources said.

The GNP has been struggling with low approval numbers amid a widespread perception that it is a party for the rich and the privileged. A series of election defeats this year deepened a sense of crisis that it could lose badly in next year's general and presidential votes.

Adding to the woes were recent revelations that an aide to one of its lawmakers was involved in a hacking attack on the Web site of South Korea's election watchdog National Election Commission.

The cyberattack paralyzed the NEC's Web site for more than two hours during the Oct. 26 by-elections.

The main opposition Democratic Party has raised suspicions that the crime must have been masterminded by higher-ranked GNP members, claiming it is hard to believe the low-level aide carried out the plot that required a lot of money to hire hacking professionals.

Reformist GNP members have called for sweeping measures to reshape the party's image, with even more members hinting at the possibility of leaving the party or even calling for splitting the party and starting a new body if adequate reforms are not carried out. (Yonhap News)