Cairo (CNN) -- Tensions soared in Egypt as an entire nation awaited presidential election results that are now expected to be announced Sunday afternoon.
"We are still going thru the complaints of electoral violations and so far we haven't determined the date of when the results will be announced," said Farouq Sultan, head of the Supreme Presidential Elections Commission, in a banner flashed on Nile TV.
Authorities are reviewing about 400 electoral violation reports submitted by the two candidates, the Muslim Brotherhood's Mohamed Morsi and former air force officer Ahmed Shafik.
Official results will be announced Sunday at 3 p.m. (9 a.m. ET), said Tarek Shibl of the election commission.
Ahead of the highly anticipated results, Egypt's all-powerful military leaders warned of potential chaos but said they won't reverse their widely deplored constitutional and judicial changes. They also warned politicians to keep a lid on election-related unrest.
"We will face anyone who will pose a challenge to the public and private sectors with an iron fist," the Supreme Council of the Armed Forces (SCAF) said.
Egypt's constitutional court dissolved the lower house of parliament last week, extending the military's power and sparking accusations of a coup d'etat.
Crowds began amassing again Saturday at Tahrir Square, jam-packed Friday night with Egyptians grown weary, impatient and angry over the election process and the military's grip on power.
They began voting in a run-off election last Saturday. A week later, with no official results announced, Cairo was awash with rumor and speculation.
Both Morsi and opponent Shafik claimed victory by small margins.
The online news site Ahram published conflicting reports on a winner.
Shafik, the last prime minister under deposed leader Hosni Mubarak, will be named the country's new president Sunday, Ahram reported on its English version Friday, citing several unnamed government sources.
But the site's Arabic version quoted election commission officials saying that Morsi remained in the lead.
"If you monitor the coverage on television and on some of the private and state on newspapers it's doomsday," said journalist Rania Al Malky, editor-in-chief of the English-language Egypt Monocle. "It's going to be a doomsday scenario if Morsi loses this election."
Al Malky said Egypt's generals are trying to paint the Muslim Brotherhood, once banned in Egypt, as cultivating instability and the side that won't respect the outcome of a democratic election.
But the Brotherhood is not staying quiet, Al Malky said, and the influential Islamic party has a lot of friends in the people who fomented Egypt's revolution last year and are willing to stand with the Islamists in an unite front against the army.
Adding to the electoral tension is the question of how much power the new president will actually wield now that the military council has full legislative authority.
Under an interim constitutional declaration, the military council retains the power to make laws and budget decisions until a new constitution is written and a new parliament elected.
The declaration said Supreme Council members "shall decide all matters related to military affairs, including the appointment of its leaders." The president has the power to declare war, it says, but only "after the approval" of the Supreme Council.
In its statement, read on state TV by a military official, the Supreme Council said the judiciary is a pillar of Egyptian society.
"All decrees issued by the judiciary system must be respected and implemented because they represent the people. It will be considered a crime if anyone objects to the ruling or attempts to block its implementation," the military said.
It said the constitutional declaration was a "necessity that the current situation posed in administrating the affairs of the nation during the critical current phase of our nation's history. Whatever is issued from SCAF is based on the high interests of the nation, nothing else."
The military council said it does not favor one political entity over another and respects the rights of Egyptians to protest but stressed the importance of self-restraint and respect for authority.
It said announcements of unofficial presidential results are "inexcusable" and sow political divisions.
The Supreme Council urged political entities to respect democracy and "abstain from all possible acts that may descend the country into a full chaos."
Egyptian reform leader Mohamed ElBaradei -- the former head of the United Nations nuclear watchdog agency and a Nobel Peace Prize laureate -- said he's been in close contact with the military council and the intelligence services on the one hand and Morsi on the other and has urged them to avoid a showdown.
He said that if Shafik, seen as a candidate of the pro-Mubarak old guard, is declared the winner, "we are in for a lot of instability and violence ... a major uprising." He isn't as worried about a Morsi victory because Shafik supporters are unlikely to take their anger to the streets, he said.
He described the current situation as "a total, complete 100% mess."