SEOUL, Nov. 23 (Xinhua) -- A political heavyweight of the ruling Saenuri Party in South Korea on Wednesday demanded President Park Geun-hye be impeached, saying he will take the lead in the impeachment within his party.

Kim Moo-sung, former Saenuri Party chairman who is seen as one of presidential hopefuls in the governing bloc, told an emergency press briefing that he will not run for presidency in next year's presidential election to take responsibility for the national chaos under the Park Geun-hye administration.

Kim said President Park betrayed people and the Saenuri Party and severely violated the constitution, noting that the president in violation of the constitution must be impeached.

He vowed to take the lead in putting forward the impeachment motion within his party.

To pass the impeachment bill through the 300-seat National Assembly, at least two-thirds of the parliamentary seat is required to vote for it. Then, over six justices of the nine-member constitutional court must endorse it to impeach a sitting president.

It would be a political challenge to opposition parties as well as the non-President Park faction of the ruling party, including Kim, because the whole procedure may take months and cause division.

Three main opposition parties already launched preparations for the impeachment. As the governing party holds almost 128 parliamentary seats, the opposition bloc is required to gain support from at least 30 Saenuri lawmakers.

Given that two of the constitutional court justices end their tenure early next year, the impeachment bill should gain approval from six of the remaining seven justices.

The division inside the Saenuri Party is getting severe. Eight former lawmakers of the ruling party seceded from their party on Wednesday after the Saenuri governor of the Gyeonggi province and one three-term lawmaker bolted from the embattled party.

Non-President Park faction members of the Saenuri Party have demanded all of the party leadership, composed of pro-Park members, immediately step down.