Fresh opposition protests are to be held in Cairo on Tuesday over a draft constitution shaped by Egyptian President Mohamed Morsi's Islamist allies that looks on track to be adopted this weekend.
Much of the judiciary is also stepping up its challenge to Morsi's authority and the proposed charter, which is being put to voters in a split referendum held last Saturday and the coming Saturday.
A group of top judges on Monday announced it would boycott supervision of the second round of the referendum. And a protest by hundreds of prosecutors forced the prosecutor general appointed last month by Morsi to tender his resignation.
The fierce opposition underlined a split in Egyptian society over Morsi and the draft constitution.
More than three weeks of protests, rallies and clashes have shaken the country and polarised it into two camps: Morsi and Islamists including his Muslim Brotherhood on one side; and secularists, liberals, leftwingers and Christians on the other.
Violent confrontations between pro- and anti-Morsi supporters early this month outside the presidential palace in Cairo killed eight people and wounded hundreds, and prompted the army to deploy troops and tanks around the compound.
The prolonged instability is badly damaging Egypt's economy as tourists, foreign investors and creditors skitter away.
The International Monetary Fund has put on pause a $4.8 billion loan, and Germany has postponed indefinitely a plan to forgive up to $316 million of Egypt's debt.
Tuesday's rallies are to take place outside the presidential palace and in Tahrir Square, focus of the revolution that toppled former leader Hosni Mubarak last year.
The opposition National Salvation Front called on Egyptians to join the protests "to defend their freedoms, prevent fraud and reject the draft constitution".
It claims the December 15 first round of the referendum was marred by numerous "irregularities and violations", including women barred from polling stations, and fake judges being used.
The Muslim Brotherhood and state media said 57 percent of voters supported the draft constitution in the first round, according to an unofficial tally, putting the text on course to be adopted in the December 22 second round.
Official results will be given only after that final stage of voting.
But for those results to be valid, polling must be overseen by judges -- and on Monday the State Council Judges Club said it would boycott Saturday's vote because the authorities had failed to live up to their promises.
The association has demanded that a "siege" of the Supreme Constitutional Court by Brotherhood supporters be lifted. But the action has continued despite the presence of soldiers and police, it said.
A sit-in by hundreds of prosecutors in Cairo's High Court also prompted the prosecutor general appointed by Morsi last month, Talaat Ibrahim Abdallah, to offer his resignation.
The Supreme Judicial Council will examine Abdallah's resignation next Sunday, a day after the final round of voting, a judicial source told AFP.
Abdallah had been appointed to succeed Abdel Meguid Mahmud, whom Morsi had sacked by decree under near-absolute powers he controversially gave himself, but which he was forced to rescind this month under pressure from the protesters.
Opposition forces had called Meguid Mahmud's firing a "coup" and judges decried it as an attack on the judiciary's independence.