“Tomorrow [Thursday] will be a great day," Hossam al-Gheriani, the head of the Islamist-dominated assembly, was quoted as saying by the BBC.
The announcement came as a surprise because last Thursday, Egyptian President Mohamed Morsi gave the assembly an additional two months time to complete its work.
Once adopted by the assembly, the draft constitution will be put to a national referendum within 15 days. A new parliament will be elected after the constitution is ratified to replace the Islamist-dominated house, according to Egypt’s political timetable.
Egypt's judiciary has been in a stand-off with Mursi after he assumed temporary sweeping powers that his supporters say will cut the turbulence in democratic transitional process but outraged critics who accused him of being a dictator.
Last Thursday, Morsi stripped Egypt’s courts of the right to challenge his decrees or annul the constituent assembly until a constitution was agreed.
Liberals, journalists, farmers and Christian churches have already boycotted the assembly, furthering the possibility of its annulment by the court.
Al-Gheriani Wednesday urged those who walked out of the assembly in protest to return.
Opposition figure and former Arab League chief Amr Moussa said the decision to issue a constitution Thursday was “nonsensical.”
"This is nonsensical and one of the steps that shouldn't be taken, given the background of anger and resentment to the current constitutional assembly,” he told Reuters.
The assembly's surprise announcement, believed to have been a result of Islamist pressure, is being criticized as a move to take the heat off the president.
It remains to be seen how the voting will be conducted in the absence of a significant number of assembly’s original members. Internal rules mandate that the first reading of the final draft should gain 67 votes and if it failed, a second reading could be based on 57 votes, Ahram Online has reported. In both cases, Islamists — Muslim Brotherhood and ultraconservative Salafists — have the majority.
On Monday, Mursi sought to defuse the backlash by calling for dialogue with the opposition and stressing the temporary nature of his decree. If the newly issued constitution passes the public referendum, the president's controversial decrees would be lifted.
The Muslim Brotherhood and other Islamist groups have called a rally Saturday in support of the president after his popularity took a nosedive following his autocratic decrees, which sparked massive protests.