Parties in the coalition government have agreed on a single version of a motion to initiate a constitutional amendment, which includes details of the formation of a panel which would write a new charter.
The fate of the Senate is to be decided in the future.
Chinnaworn Boonyakiat, deputy government chief whip, on Thursday said the version of the motion will be forwarded to parliament for approval after the Council of State, the government's team of legal advisers, finishes its review of its wording.
The government-sponsored motion would allow the formation of a 200-member charter-drafting panel made up of 150 elected writers, the Democrat MP for Nakhon Si Thammarat said, adding senators, university presidents and the student movement would choose 50 others.
The panel would have 240 days to write a draft for constitutional amendments, the passing of which would be determined via a referendum if parliament votes to reject it.
The motion was made following the opposition-sponsored version, which would leave the Senate's fate in the hands of the writers, Mr Chinnaworn said.
An amendment to Section 256 is needed to open the door to a constitutional amendment by a new committee.
Section 256 stipulates charter amendment requirements, including a national referendum if a would-be amendment involves the chapters on general provisions, the king and charter amendment.
The charter amendment process was set in motion after students kicked off a series of anti-government protests last month. One of their demands was to rewrite the constitution, which was enacted by the previous government under coup-leader Prime Minister Prayut Chan-o-cha.
The opposition camp submitted its version of the motion to House Speaker Chuan Leekpai on Aug 17.
The looming controversial issue is the future of the Senate. The Move Forward Party has vowed to curb its power, or even get rid of the upper house.
The current constitution gives extensive power to senators, all non-elected, including entitling them to vote during the selection of the prime minister.
Although the coalition parties will support a joint motion which leaves the Senate untouched, members of the Democrat Party remain defiant in wanting to limit the role of senators.
The party will decide on Monday.