SEOUL, March 15 (Xinhua) -- Three South Korean political parties, excluding the biggest opposition Minjoo Party, on Wednesday agreed to a national referendum on the constitutional amendment.
Floor leaders of the Liberty Korea Party, ousted President Park Geun-hye's party, and its splinter Righteous Party as well as the minor opposition People's Party met earlier in the day, agreeing to the referendum.
The three parties agreed to hold the referendum on the date of presidential election, which is forecast to be held on May 9.
Push for the constitutional revision is aimed at weakening the power of president, called imperial president here, as the three parties have little chance to win in the presidential race.
The draft amendment calls for the four-year, two-term presidency, while discussing the shortening of next leader's tenure to three years for the launch of the amended constitution. Currently, a president here serves a single, five-year term.
Public support for the Liberty Korea Party and the Righteous Party, composed of defectors from the Liberty Korea Party, has tumbled since the corruption scandal embroiling Park emerged in late October.
The support scores declined further after Park's impeachment motion was unanimously upheld on Friday by the constitutional court, dimming the outlook for the conservative parties to win back presidency.
A presidential election must be held within 60 days as the president is formally unseated.
Approval rating for the People's Party, which broke away from the main opposition Minjoo Party, also hovered at a low level even after Park's ouster by the court.
Three major presidential contenders of the Minjoo Party have gained about 60 percent of public support in total in recent opinion polls, with the party's approval scores soaring to almost 50 percent.
The winner in the primaries of the Minjoo Party is expected to become the next South Korean leader to succeed Park.
The bill on constitutional revision can be tabled in the 300-seat National Assembly if at least 150 lawmakers agree on it. It would be passed if over two-thirds of the parliament votes for it.
The Minjoo Party has 121 parliamentary seats. It was trailed by the Liberty Korea Party with 93 seats, the People's Party with 39 seats, the Righteous Party with 33 seats and the Justice Party with six seats.