The United States has urged Egypt's military to move swiftly on plans to transfer full power to an elected civilian government and suggested failure to do so would prompt a review of US ties, which includes billions of dollars in military and civilian aid.
Both the US State Department and the Pentagon - which oversees the close military links between the two countries - voiced concerns on Monday over moves by Egypt's generals to tighten their grip on power despite a presidential vote aimed at sealing the country's democratic future.
The military power grab represents a dilemma for the Barack Obama administration, which publicly backed the revolution that toppled longtime leader Hosni Mubarak last year but also sees the Egyptian army as a crucial regional security partner.
At the same time, some in Washington may share the Egyptian military's wariness of the Muslim Brotherhood, a popular Islamist group whose candidate some reports said was leading in Egypt's presidential vote.
The Brotherhood has called on people to protest against what it calls a "coup" by the ruling generals, as the country awaits the publication of official results from the weekend's presidential election.
The Supreme Council of the Armed Forces, or SCAF, has granted itself a number of sweeping powers, including control of the budget and the army. Even so, it repeated on Monday its pledge to hand over authority to a civilian government by the end of the month.
Mohammed al-Assar, one of the generals, said during a lengthy press conference in Cairo that there would be a "grand ceremony" to mark the transition.
"We'll never tire or be bored from assuring everyone that we will hand over power before the end of June," he said.
According to a decree issued on Sunday night, SCAF will retain authority over the budget and the legislative process until a new parliament is elected,
The decree even limits the new president's powers as commander-in-chief, stating that he can only declare war "with the approval of the military council".
Sameh Ashour, the head of SCAF's advisory council, said the incoming president would probably have a short term, and would be replaced after a new constitution was drafted.
"The upcoming president will occupy the office for a short period of time, whether or not he agrees," he told Al Jazeera. "His office term will be short despite the huge efforts exerted in the election campaigns."
It still is not clear, nearly 24 hours after polls closed, who that next president will be.
Against this backdrop of deepending uncertainty, the US said it was deeply concerned about the situation in Egypt.
Mohammed Morsi, the Muslim Brotherhood's candidate, claimed victory in the early hours of Monday morning.
The Brotherhood's unofficial tally had Morsi leading with about 12.7 million votes, or 52.5 per cent of the total. Several other counts from media organisations, including Al Jazeera, also showed Morsi with a narrow lead.
"Thank God, who guided the people of Egypt to this right path, the path of freedom and democracy," Morsi said during his victory speech, vowing to work for a "civil, democratic, constitutional and modern state".
The Brotherhood said it was confident in its figures, and indeed their unofficial counts have been accurate in past elections. "Our official numbers in round one matched exactly the [presidential election commission's] final numbers," the group said in a statement.
But his opponent, Ahmed Shafiq, the final prime minister under deposed president Hosni Mubarak, rejected Morsi's claim of victory and accused him of trying to "usurp" the presidency.
"What the other candidate has done threatens Egypt's future and stability," he said in a statement.
Shafiq's campaign said their own internal figures showed their candidate leading with about 52 per cent of the vote, and accused Morsi's camp of miscounting millions of ballots.
The generals did not address the electoral confusion during Monday's press conference. They instead tried to rebut criticism of their decree, a so-called "constitutional annex" which will govern the country until a new constitution is drafted.
Mamdouh Shahin, another of the generals, said that the president would still have the authority to ratify or reject any laws approved by SCAF.
Supreme Court ruling
SCAF dissolved parliament last week following a ruling by the supreme court, which found the legislature unconstitutional.
The court ruled that provisions of the electoral law - which allowed political parties to compete for seats reserved for independent candidates - violated the constitution.
With the legislature gone, the generals reasserted control over the legislative process, and over the country's budget.
"The Supreme Council of the Armed Forces shall exercise the powers referred to under the first clause of article 56 [the article on legislative power] ... until the election of a new People's Assembly," the decree states.
The decree promises fresh legislative elections, but not until a new constitution has been drafted.
Before it was dissolved, the parliament appointed a 100-member assembly to draft that constitution; it will be allowed to continue its work, though if it runs into "obstacles", SCAF will appoint a replacement.
The Muslim Brotherhood was quick to condemn the decree, calling it "null and unconstitutional" in a brief statement on Twitter.
Asked about the decree during the group's press conference, Ahmed Abdel-Atti, Morsi's campaign co-ordinator, said he expected "popular action" against it in the near future.