U.S. President Barack Obama is urging Egyptian leader Mohamed Morsi to show he is responsive to the concerns of opposition protesters.
Egypt has seen several days of massive demonstrations, with many of those opposed to Morsi calling for him to resign. Violence has broken out in some areas, leaving at least 16 people dead.
The White House said Obama expressed his concerns to Morsi in a telephone call Monday, saying that the United States backs a democratic process in Egypt and does not support any single party or group.
Obama also said he was deeply concerned about the violence, particularly sexual assaults against women.
Morsi's office rejected an ultimatum issued Monday by the military for the president and opposition leaders to settle their differences in 48 hours and agree on a path forward.
Defense Minister General Abdel Fattah el-Sissi said if no deal is reached, the military will present its own road map for Egypt's future.
Morsi's office said he will stick to his plan for national reconciliation, regardless of "statements that deepen divisions between citizens."
Opposition leaders have also given President Morsi until 5 p.m. Cairo time on Tuesday to resign.
Early Tuesday, Egyptian media reported that Foreign Minister Mohamed Kamel Amr submitted his resignation letter. At least four other ministers have resigned since Sunday.
Millions of people took to Egypt's streets on Sunday in the largest anti-government demonstrations since the 2011 revolution that swept former President Hosni Mubarak from power.
Opponents of President Morsi have been massing in Cairo's Tahrir Square, many of them urging him to resign. His supporters have been gathering in the Nasr City section of Cairo, voicing support for the government and concerns about the possibility of strong military intervention.