The process of amending the constitution and making laws organic in the new charter is expected to be complete by July 2022.
Deputy Prime Minister Wissanu Krea-ngam, who is the government's expert on legal affairs, on Thursday provided a tentative time frame for the charter rewriting process.
Mr Wissanu said while the version of the charter amendment bill from the main opposition Pheu Thai Party seeks to establish a charter-drafting body and have a new constitution rewritten by it within 120 days, the version of the bill presented by government-coalition parties sets a 240-day time frame for drawing up a new charter.
Parliament is expected to deliberate both versions during their first reading on Sept 23 and 24, he said.
Both bills are expected to be combined into one during the parliament reading session.
However, Mr Wissanu said the charter amendment process may take a long time because even if both bills are endorsed by both houses of parliament, they will have to wait until a separate bill on a referendum on the charter rewrite is enacted before they are put to the vote.
"This will take a long time," he said.
On Tuesday, the cabinet approved a draft bill to pave the way for a referendum on the rewrite of the charter.
The bill is being scrutinised by the Council of State -- the government's legal advisory body, Mr Wissanu said, adding the secretary of the council is expected to finish vetting the bill within 30 days.
The bill will be tabled to parliament on Nov 1, when MPs reconvene its new session, he said.
After the bill is royally endorsed and enacted, a referendum must be held within 120 days, Mr Wissanu noted.
If anyone challenges the outcome of the referendum, the matter must go to the Constitutional Court, which is expected to take less than a month to deliver a ruling.
When the matter is cleared in court, the charter amendment bill will be submitted for royal endorsement -- a process which takes up to 90 days before the charter drafting body is formally set up and goes about its job.
Mr Wissanu said Pheu Thai's version of the charter amendment bill calls for another referendum on the draft of the new charter.
But the coalition parties' version calls for the new charter draft to be voted on in parliament.
If the charter draft is approved by more than half of MPs, there is no need for a referendum.
If it does not win support, a referendum must be held within 60 days, Mr Wissanu said.
Another 30 days will also be required for interpretation by the Constitutional Court and another 90 days for royal endorsement of the new charter, he said.
This is not to mention the redrafting of at least three laws organic to the constitution -- one on the Senate, another on political parties, and another on the election of MPs, he added.
