Egypt's political forces have called for more protests on Friday against the ruling military's power grab, as the nation nervously awaits the results of the first post-Mubarak presidential election.
Hundreds of people spent the night in Cairo's Tahrir Square, with more protests planned for Friday afternoon, the Muslim Brotherhood and secular movements said in statements.
The ruling Supreme Council of the Armed Forces (SCAF), which took power when Hosni Mubarak was ousted last year, will issue a statement at 1130 GMT, state television said without providing any details, as anger mounts over the perceived threat to the fragile democratic gains made since the uprising.
The Muslim Brotherhood, which claimed its candidate Mohamed Morsi had won the divisive election against ex-premier Ahmed Shafiq, has been holding crisis talks with the country's political forces.
It is due to announce "a national project to defend the revolution," its political arm the Freedom and Justice Party (FJP) said.
Morsi also spoke by telephone with Nobel laureate and reform campaigner Mohamed ElBaradei, as well as with former presidential hopeful Abdel Moneim Abul Fotouh ahead of the protests, the FJP said.
The April 6 movement, which helped launch last year's uprising that toppled Mubarak, said it would join the protests to express "its rejection of the constitutional declaration" and "continue to fight for the goals of the revolution."
The National Front for Justice and Democracy said it rejected the constitutional declaration "which constitutes a military coup."
A recent set of measures consolidating the army's power has infuriated pro-democracy groups and raised concerns abroad.
The ruling SCAF assumed legislative powers after a court ordered the Islamist-led parliament dissolved and issued decrees giving the army powers of arrest and a broad say in government policy, rendering the president's post toothless.
Protesters have been in Tahrir Square since the constitutional document was issued on Sunday.
The tension comes as the country waits to find out who will be the next president, after the election commission failed to announce the results on Thursday, saying it needed more time to look into appeals by both candidates.
Morsi's rival Shafiq -- Mubarak's last prime minister -- said he was confident he would be declared the "legitimate" president, raising fears of unrest in a country exhausted by political upheaval and insecurity of the transition from Mubarak's rule.