The Democrat Party on Sunday urged the regime to spell out an exact date for a general election to ward off scepticism about the government's efforts to relinquish its powers.
Democrat deputy leader Sathit Pitutecha said that although the regime has repeatedly said it will stick to its political roadmap leading up to the poll, and has recently put a new charter into effect, it risks having its credibility undermined by not giving a specific timeframe for the election.
Mr Sathit also called on the regime to move boldly to tackle graft in the military and avoid dedicating too much of the national budget to populist policies.
The new charter was royally endorsed by His Majesty the King and promulgated on April 6. The Constitution Drafting Committee (CDC) is now required to draft four organic laws that are needed for the general election to be held. This must be done within 240 days of the constitution's promulgation.
The organic laws must then be forwarded to the National Legislative Assembly for scrutiny.
Nipit Intarasombat, another deputy leader of the party, said he much doubted the CDC would act quickly in preparing the laws.
He said he could not hazard a guess as to when the election would be held but he suspected it would be a drawn-out affair.
"I do not want to make any guesses or speculate on this or that," Mr Nipit said.
"I only see that in every [public opinion] poll, people are talking about when the election will be held in the wake of the charter being promulgated."
Nikorn Jamnong, an executive of the Chartthaipattana Party, said his party has no problem with the poll being held in the middle of next year.
Prime Minister Prayut Chan-o-cha has made comments indicating this is a strong possibility.
This would give the Chartthaipattana Party enough time to amend its regulations to comply with the new laws governing political parties and the charter, Mr Nikorn said.
Meanwhile, Deputy Prime Minister Prawit Wongsuwon on Thursday will meet four committees dealing with the subject of national reconciliation.
Opinions from the public sector will also be presented at the meeting, said Gen Chaicharn Changmongkol, permanent secretary for defence.
He said he expects a deal to be finalised in June as planned.