Constitution Drafting Committee chairman Meechai Ruchupan has denied saying people should vote to adopt the draft charter and then push for any amendments they wish to make.
Mr Meechai maintains his statements to the National Legislative Assembly (NLA) were misinterpreted.
During his Friday address to the NLA, he said that, at this time, there was nothing that could be done to change the draft charter. He added that if there were any mistakes or shortcomings, the constitution would be amended in the future.
Mr Meechai made it clear that he never declared the draft charter should be accepted in the Aug 7 referendum and be amended later, as anti-government groups and some Pheu Thai politicians alleged.
He said constitutional amendments may be required in future as the country's situation changes, adding his critics were determined to find fault with the charter instead of focusing on the national interest.
He said the Election Commission (EC) is in charge of enforcing the referendum law, including with regards to a reported plan by some activists to launch a T-shirt campaign encouraging people to vote "No" in the referendum.
Mr Meechai said the CDC will not send a representative to debate the contents of the draft charter with the anti-coup New Democracy Movement. He suggested the group should finish reading the entire draft before "throwing down the gauntlet".
"I fail to see the merit in arguing the points with anyone who has only read three pages of the entire [draft charter] book and then assumed the writer was up to no good," he said.
Prime Minister Prayut Chan-o-cha yesterday said a rejection of the draft charter at the referendum would not provide him with the pretext to prolong his hold on power.
Meanwhile, the EC yesterday launched a mobile phone application that gives people access to the contents of the draft charter and also provides information about the referendum.
Speaking at the "Smart Info" application launch, EC member Somchai Srisutthiyakorn said the app shows information in text format and info-graphics, with a focus on referendum procedures.
Mr Somchai said the app also features information regarding referendum laws and regulations as well as the vote-counting system.
The app is now available for download on both Android and iOS. Users can also download it by scanning a QR code via Line.
Mr Somchai said the app can also link users to other EC applications like "Dao Nua", which informs voters about their referendum polling stations, and "Ta Sapparot", which can be used to alert authorities of voting fraud.
Voters can also register to vote outside their districts via the Smart Info app, he added.
Also yesterday, the EC deployed teams to clarify voting procedures to the public, including the elderly and disabled.
If there are more than 100 disabled or elderly people within a community, a request can be made to have a special polling station set up.
The station will be equipped with facilities such as ID card readers, walkers, magnifying glasses and wheelchair-accessible voting booths.