Egyptian judges are investigating opposition accusations of voting fraud before declaring the result of a referendum set to show that a contentious new constitution has been approved.
President Mohamed Morsi sees the basic law, drawn up mostly by his Islamist allies, as a vital step in Egypt's transition to democracy almost two years after the fall of military-backed strongman Hosni Mubarak.
Unofficial tallies from the Muslim Brotherhood - which catapulted Mr Morsi into the presidency this year - indicated that 64 percent had approved the charter, although an official result was not expected until at least tomorrow. An opposition tally had a similar result.
Mr Morsi's critics said the vote, conducted in two stages in a process that ended on Saturday, had been marred by a litany of irregularities, and have demanded a full inquiry.
"The committee is currently compiling results from the first and second phase and votes from Egyptians abroad, and is investigating complaints," Judge Mahmoud Abu Shousha, a member of the committee, said.
Two sources in the committee said the results were likely to be announced tomorrow. "It will not be very different from the unofficial result, at 60-something percent," one said.
The opposition, a loose alliance of socialists, liberal-minded Muslims and Christians, say the text is too Islamist, ignores the rights of minorities and represents a recipe for more trouble in the most populous Arab nation. They have noted that less than a third of those eligible turned out to vote.
If the "yes" vote is confirmed, a parliamentary election will follow in about two months, setting the stage for Islamists to renew their battle with more secular-minded opponents.
Opposition politician Mohamed ElBaradei, a Nobel peace prize winner, urged Mr Morsi to form an all-inclusive government together with the liberal camp in order to patch up divisions and steer Egypt out of trouble in a democratic way.
By forcing the pace on the constitution, Mr Morsi risks squandering the opportunity to build consensus for the austerity measures desperately needed to kick-start an ailing economy, economists say.
Highlighting investor concerns, Standard and Poor's cut Egypt's long-term credit rating and said another cut was possible if political turbulence worsened.
Responding to what it said were market rumours, the central bank said it was taking steps to safeguard bank deposits.
Some Egyptians say they have withdrawn their funds from banks out of concern that they will be frozen by authorities.
Reuters