"What is more important than extending the panel's term is for the LKP to present its clear position on the public referendum to be held in tandem with the local elections," Rep. Park Hong-geun, the vice DP floor leader, told Yonhap News Agency over the phone.

Amid the main opposition party's lack of interest in the revision dialogue, speculation has grown that the ruling party could seek to foster solidarity on the issue with other parties, such as the People's Party and Bareun Party, to galvanize the LKP's participation.

"If the LKP insists it cannot agree to the idea of holding the referendum during the local elections, we cannot help but pursue a different way (to pressure it)," a senior ruling party official said, declining to be named.

"We can, perhaps, weigh the option of creating a tie-up with the parties that share the need for the revision so as to put pressure on the LKP," he added.

The ruling party, which has only 121 seats in the 299-member National Assembly, needs the LKP's cooperation in the passage of any revision bill.

Tabling the proposal for a constitutional change requires backing from a majority of all lawmakers. The parliamentary passage needs support from two-thirds of the total legislators. It then has to win majority support in a referendum involving a majority of eligible voters.

The discussions over the revision center on reshaping the governance structure to diffuse the power that is concentrated in a president.

Some lawmakers have called for introducing a semi-presidential system -- a mixture of the presidential system and parliamentary cabinet system -- under which more power is assigned to the prime minister. Others have espoused a purely parliamentary Cabinet system like in Japan.

During his election campaign, President Moon Jae-in called for changing the current single-term, five-year presidency into a four-year presidency that allows for only one re-election. He has said the change would help ensure consistent policy implementation with long-term visions.