Charter amendment panel member Chinnaworn Boonyakiat on Friday voiced his opposition to a motion seeking a judicial review of two accepted charter amendment drafts.
The motion, signed by 47 senators, as well as 25 MPs from Palang Pracharath -- the main coalition party -- was widely seen as an attempt to derail the charter amendment process.
It claimed parliament was not authorised to "draw up" a new charter and any attempt to allow the writing of a new one would be unconstitutional, he said.
"I disagree with the motion. I believe the charter amendment bill, which is sponsored by the coalition government, is in compliance with the charter. But the issue is just a difference of opinion," said the Democrat MP for Nakhon Si Thammarat.
Only two drafts, one sponsored by the government and another by the opposition bloc, were passed in the first reading. Both proposed to amend Section 256 to make way for the setting up of a charter drafting assembly (CDA) to draw up a new constitution.
The motion to seek a Constitutional Court ruling on the legality of these two drafts was supposed to be considered by parliament last month, but was postponed.
Mr Chinnaworn said the second reading of the charter amendment bills would not be chaotic as some fear after only 109 lawmakers signed up to voice their opinions during the second reading.
He said the charter amendment committee has yet to complete its task and these lawmakers might eventually agree with the panel's proposed changes to them when they are ready for the second reading.
The second reading is tentatively scheduled for January.
The Democrat MP also said parliament president Chuan Leekpai would make sure the debate was orderly and not repetitive.
Meanwhile, Democrat leader Jurin Laksanawisit said it would be up to the charter amendment panel to decide if the proposed CDA should be appointed or elected.
The CDA in the government-sponsored draft would comprise 200 members: 150 elected, 20 picked by parliament, 10 public law experts, 10 political experts and 10 representatives from student groups.
The one proposed by the opposition would be made up of 200 members, all directly elected.