A senator has called for Upper House involvement after both government and opposition MPs proposed separate motions to set up a committee to study constitutional changes.
Senator Kamnoon Sidhisamarn was commenting on a vote on Friday by the House of Representatives to prioritise debate of the charter amendment motions during the next House session in November.
Mr Kamnoon on Saturday said he wanted the Senate to be represented on the committee, citing a charter provision which stipulates that a constitutional amendment needs a vote of support from at least one-third of senators in the first and third readings.
"A joint MP-Senate committee can be set up under the parliament's meeting regulations or at the behest of the parliament president,'' Mr Kamnoon said.
He also shrugged off a motion proposed by some MPs to deny the Senate a role, saying the constitution guarantees the Senate a vote on charter amendments.
Senator Seree Suwanpanon, who chairs a Senate committee on political development and public participation, said a subcommittee will be set up to monitor the push to amend the constitution by the House and also present suggestions.
Pheu Thai Party leader Sompong Amornwiwat brushed aside criticism from the government that the opposition has become so obsessed with amending the charter that it is failing to address bread-and-butter issues affecting people.
Mr Sompong said the economic problems facing the country are the result of the military coup five years ago, and stressed that attempts to see the charter rewritten will proceed in parallel with efforts to bring the nation out of a slump.
Deputy Pheu Thai leader Samart Kaewmeechai said that both opposition and government MPs are pushing for charter amendments because the current constitution is undemocratic and cannot steer the country forward.
"The now-defunct Constitution Drafting Committee drew up the charter to help the military regime stay in power," Mr Samart said.
On Friday, the House agreed by a vote of 425-0 to address the motions for constitutional amendment as a priority at its next session in November.
The motions were separately put forward by the Pheu Thai-led opposition and the ruling Palang Pracharath Party and coalition partners the Democrats.
However, observers noted the constitution will be difficult to amend, especially regarding the role of 250 senators appointed by the coup-makers.