The coalition government on Wednesday called for support from senators for their proposed charter amendments, to defuse potential political conflict.
Government chief whip Wirat Rattanaset and Bhumjaithai Party MP Supachai Chaisamut emphasized the need to amend the constitution by setting up a new team of charter writers, as a way out of the political conflict dividing the country.
Mr Wirat, a Palang Pracharath MP, said backing from the Senate was needed to pass the government-sponsored bill in the first reading.
The two key MPs of the government wing made it clear the coalition wanted the first two chapters of the constitution left untouched.
"The charter amendment must not touch Chapter 1, on general provisions, and Chapter 2, on the monarchy," Mr Supachai said during the joint session of parliament.
Part of the first chapter and the entire second chapter of the constitution state the power and role of the monarch.
The Move Forward Party supports the inclusion of the two chapters in the future amendment, in line with demands by student-led protests for reform of the monarchy.
Move Forward leader Pita Limjaroenrat said the amendment of the first two chapters would bring about a constitutional monarchy that would remain at the centre of the nation with no involvement in politics.
The government-sponsored bill is one of the six charter amendment drafts being debated before the joint session votes on Thursday. The other versions are backed by the opposition. They call for the amendment of the entire charter through a new assembly of writers, or only some sections.
One of the controversial issues supported by the oppostion camp is to end the role of the Senate in participating in the voting for a new prime minister, along with the House of Representatives. The opposition argues this is a choice for MPs alone to decide. (continues below)
Pushing a charter amendment bill through the first reading is not a simple matter. It needs the participation of the Senate. The current constitution requires a majority vote by a joint sitting, including support of one-third of the upper house, or 84 senators.
The joint chambers will vote on Thursday, with each member being called by name to say whether they support or reject each version of the draft amendment.
Many senators have objected to attempts of the opposition to "switch off" their role, deeming the move to void the present constitution a betrayal of the majority who voted for it at the referendum.
Protest leaders have called for a rally outside parliament on Thursday, to put pressure on lawmakers to support charter amendments.