An Egyptian court meant to rule on Tuesday on the fate of an Islamist-dominated panel has instead referred the case to a superior court which has already expressed its opposition to the draft charter.
The case has widened a rift between the ruling Islamists and secular-leaning opponents over the role of religion in the text that led to skirmishes this month during rival rallies in Cairo.
In a brief court session, a judge with the Supreme Administrative Court said he had decided to refer the case to the constitutional court, which has said it opposes provisions in the draft charter regulating the judiciary.
"Down with the Constituent Assembly," chanted a dozen opponents of the assembly after the judge read his decision.
No date was set for the verdict on the constitutionality of the 100-member Constituent Assembly in charge of writing the constitution, amid a power struggle between the judiciary and Islamist President Mohamed Morsi.
The Assembly is being challenged over the mechanism with which its members were chosen.
It is the second Constituent Assembly formed since the uprising that toppled president Hosni Mubarak last year, after an Islamist-dominated panel was dissolved in April for failing to represent all segments of society.
"A constitution is made to last," former Chief Justice Ahmed Medhat Elmaraghy recently told AFP. It "should have been made up of legal experts, but this did not happen."
"It has been dominated by the Islamists, but the constitution has to be a matter of national consensus."
The panel released a draft constitution earlier this month that was slammed by human rights groups as failing to secure key freedoms.
Some articles, including those defining the powers of the judiciary and the role of the army, have not been made available to the public.
Other contentious topics include the role of religion, the status of women and the scope of freedom of expression and faith.
Article 2 of the draft constitution states that "Islam is the religion of the State, Arabic is its official language and the principles of Islamic Sharia form the main source of legislation."
Ultraconservative Islamists had asked to replace "the principles of Sharia" by "the rulings of Sharia" or even just "Sharia."
The article has been at the centre of debates because it opens many avenues for the interpretation of Sharia.
Mona Makram Ebeid, a veteran politician who pulled out of the first assembly, said the text "fails to protect the rights of women and the character of a civil state."
"What is unbelievable is that all the mistakes of the first assembly are present in the second one."
Last week, Egypt's highest court criticised the panel, saying some of its proposals put the court back under the authority of the president.
"The proposed text gives the president the right to appoint the chairman and members of the court," said court chairman Maher al-Beheiry, adding that this allows the president to interfere in its work.
"Last year we finally got an amendment that does not allow the president to name the chairman and members of the court without the approval of its general assembly."
The criticism came amid tension between Morsi and the judiciary, after he failed last week to remove public prosecutor Abdel Meguid Mahmud.
Mahmud refused to step down after Morsi ordered his removal to allay public anger over acquittals of officials from Mubarak's ousted regime.
Morsi had issued a presidential decree appointing Mahmud as Egypt's envoy to the Vatican.
The new constitution is to replace a 1971 charter suspended by the military, which took power when Mubarak was ousted in February last year.