"The party wants a neutral panel to rewrite the Constitution and a referendum on the draft amendments before enactment without the party's involvement," he said.

Bhokin said his party would unveil its proposed plan after the Songkran holiday and expected to fine-tune it by factoring in public criticisms before putting it into action.

He promised to heed counter proposals, including those from the Democrat Party.

The charter rewriting is expected to start following the convening of Parliament, which will take place only after the completion of the electoral process for the 500-seat House of Representatives and the 200-seat Senate.

Under Bhokin's tentative plan, the joint House-Senate session will be convened to amend Article 313 of the Constitution paving the way for a neutral panel to take charge of the charter rewrite.

At present, only the Cabinet and elected lawmakers can sponsor draft amendments.

The formation of the neutral panel remains a contentious issue between the ruling party and the three former opposition allies, the Democrat, Chat Thai and Mahachon parties.

According to Bhokin, an assembly of professional groups should be formed. It would be modelled on the National Convention, or Sapha Sanam Ma, created by late premier Sanya Dharmasakti following the 1973 student uprising.

The model of the 99-member Constitutional Drafting Assembly, which took charge for the drafting of the 1997 Constitution, is deemed inappropriate because Parliament would elect its members. And the incoming Lower House will be completely dominated by the ruling party.

Should the National Convention model be acceptable, some 100 members will be nominated by 2,000 professional groups registered under the law governing the National Economic and Social Advisory Council (Nesac).

Additional professional groups may join the nomination process under the care of five secretary-generals. The five will be from the House Secretariat, the Senate Secretariat, the King Prajadhipok's Institute, the Council of State and the Nesac.

In addition to 100 assembly members, another 20 will include representatives from the courts and independent organisations, as well as experts on law and public administration.

The 120-member assembly will then elect a panel of charter writers and scrutinise the draft. Its vetted draft will go straight to a referendum, bypassing Parliament.

Bhokin said his party instructed him to solicit opinions of leading figures in society in order to ensure neutrality in the drafting process.

Some party executives called for a neutral panel of former prime ministers and former Supreme Court presidents to assist in screening the assembly members, he said.

He said he was willing to implement a drafting process deemed appropriate by society rather than pushing for his own ideas.

He said he was reluctant to involve the Privy Council in nominating the neutral panel for constitutional amendments but would abide by the judgement of society.

"The involvement of the Privy Council is in line with the Democrat's proposed process and will be implemented if society says so," he said.

Based on the original idea of law expert Amorn Chandarasomboon, the Democrat Party proposed the Privy Council nominate a seven-member panel to draft constitutional amendments.