Prime Minister Prayut Chan-o-cha launched a stinging rebuke Tuesday against political party leaders who oppose the formation of a "crisis panel" in the new draft charter.
Speaking after a cabinet meeting, Gen Prayut said politicians have no right to try and persuade the National Reform Council (NRC) to reject the draft.
His comment followed fierce criticism from key politicians, particularly Democrat Party leader Abhisit Vejjajiva and former prime minister Yingluck Shinawatra.
"Politicians have nothing to do with this. Several of them are already facing court cases, but it seems they fear nothing.
"These people are harsh against me so I'll have to be just as harsh against them. Don't flee justice when you are prosecuted," Gen Prayut said.
"Several politicians said they won't run in elections [after the charter is enacted]. Remember what you said and let's put their words on the record," the prime minister said.
Opposition is mounting against the draft charter, particularly a provisional clause to establish the National Strategic Committee, widely known as the crisis panel.
While the charter drafters have hailed the proposal for the new committee as a means to resolve future political crises, critics have condemned it as undemocratic and a way to help the coup-makers to remain in power.
The 23-member National Strategic Committee will include the army, navy, air force and police chiefs.
Section 280 of the draft gives the panel special powers after the new charter has been enacted to intervene in a political crisis by seizing both executive and legislative powers from the government and parliament if they believe the government cannot function and national administration is seriously compromised.
The special powers last for five years after the charter is enacted.
A two-thirds vote is needed for an intervention to take place.
The draft charter is now with the NRC, which will vote on it on Sept 6.
If more than half of the 248 NRC members approve the draft, a referendum to allow the public to decide on its fate is expected to be held in January.
But if the NRC votes against it, a new team of charter drafters will be appointed to write a new charter within 180 days.
Regardless of the outcome, the NRC will be dissolved after the vote.
Earlier Tuesday, Mr Abhisit called on the NRC to reject the draft charter on Sept 6.
The former prime minister said he wants the NRC to reject the draft charter, not because he wants Gen Prayut to stay on in power, but because it needs to be revised before being put to a referendum.
He does not mind that an elected government would be supervised by a panel, and that the new charter would force a newly elected government to push ahead with national reform.
However, the draft charter does not lay out what reforms it wants.
"What will happen if a political amnesty was proposed like in the past [as part of reforms]?" he said.
The draft charter could bring about several problems in the future as it has several loopholes, he said.
The formation of a crisis panel would also lead to problems and conflicts, as it would be "a state within a state".
The draft charter has to be designed to prevent abuses of power by the panel, he said.
The NRC should vote to reject the draft constitution and set up another 21-member committee to revise it, while sticking to the aim of national reforms, maintaining peace and order, and ensuring a smooth transition to democracy, Mr Abhisit said.
He believes the revision should take only two or three months, after which a referendum could be held.
Ms Yingluck also said Tuesday the draft charter should be rejected.
The draft is out of touch with the people, she said.
The ousted premier added an undemocratic constitution would put the brakes on the country's progress.
"And I, who came to power through an election, do not agree the charter should be pushed through.
"What the people want is empowerment and the right to make their own decisions," she said.
It is too soon to say whether the Pheu Thai Party would campaign for a no-vote if a national referendum on the draft is held, she added.
"In any case, I would like the roadmap to be clearer, not extended.
"The longer it is, the more pain people will have to endure, especially low-income people, who have little tolerance [for economic difficulties]," she said.