Kim suspected that the president has fixed the submission date based on his schedule for a six-day trip to Vietnam and the United Arab Emirates, which begins on Thursday.

"This is an example of how lightly he has viewed the revision issue," Kim said.

Kim also renewed his party's opposition to Moon's push to hold the referendum at the same time as the local elections. The LKP maintains the revision issue needs more thorough deliberations, and that holding the referendum concurrently with the June elections will run the risk of politicizing the constitutional change.

The revision of the basic law needs the LKP's cooperation, as it requires approval from two thirds of all 293 lawmakers in the unicameral National Assembly and a majority of voters in a referendum. The ruling Democratic Party has only 121 parliamentary seats, just five more than the LKP.

Given the parliamentary dynamics, some LKP members suspect that Moon's stepped-up push to table the government's own bill is part of a political ploy to cast their party as an "anti-reform" group and shirk responsibility for any failure in the revision efforts.

The progressive Justice Party, seen as largely sympathetic to Moon's policy stances on security and other fronts, also opposed the prospect of the government leading the constitutional revision.

"What the ruling party has to do is not to give an ultimatum by offering the March 26 deadline, but exercise its political capacity," Lee Jung-mi, the party leader, said, stressing that the submission should proceed based upon agreement among all ruling and opposition parties.

The minor opposition Bareunmirae Party also joined the criticism.

"The government and ruling party have to make their joint proposal for revision and engage in sincere negotiations (with opposition parties)," Kim Cheol-kun, the party's spokesman, said in a commentary.

Countering the opposition parties' attacks, the ruling Democratic Party condemned them for "throwing cold water on people's request" for the revision.

"The parliamentary panel on the revision has discussed the revision issue for the last 15 months ... Thus, their argument that they need more time and more discussions does not make sense," Choo Mi-ae, the party's leader, said.

"Now what is left for us to do is the last negotiations and determination," she added.

A major bone of contention is how to address the current concentration of state powers in a single leader, which has been blamed for corruption, power abuse and intense political polarization.

The ruling bloc seeks to change the current five-year presidency into a four-year term that allows for one reelection. But the LKP has advocated for a power-sharing model under which more authority is given to a prime minister picked by parliament. (Yonhap)