But on his Facebook page, Morsi's top foreign policy adviser Essam al-Haddad wrote, "For the sake of Egypt and for historical accuracy, let's call what is happening by its real name: Military coup."
At the main pro-Morsi rally in Cairo, thousands of his Islamist supporters chanted, "Wake up el-Sissi, Morsi is my president."
"We will not bring back the military rule," they chanted outside the Rabia al-Adawiya Mosque. "Will not happen, will not happen," they shouted.
The army has insisted it is not carrying out a coup, but acting on the will of the people to clear the way for a new leadership. Under a plan leaked to state media, the military would install a new interim leadership, the Islamist-backed constitution suspended and the Islamist-dominated parliament dissolved.
But on Wednesday it clearly was positioning itself to maintain control during any unrest sparked by a move on Morsi.
The military beefed up its presence inside the mammoth headquarters of state TV on the banks of the Nile in central Cairo. Crack troops were deployed in news production areas. Officers from the army's media department moved inside the newsroom and were monitoring output, though not yet interfering, staffers said, speaking on condition of anonymity because they were not authorized to talk about the arrangements.
State TV is run by the information minister, a Muslim Brotherhood member appointed by Morsi, and its coverage had largely been in favor of the government. But in the past two days, the coverage saw a marked shift, with more balanced reporting showing anti-Morsi protests along with those supporting him. State radio has seen a similar shift.
The state-run Al-Ahram newspaper — which also seemed to be following a military line — reported that the military had placed several leaders of Morsi's Muslim Brotherhood under surveillance.
The paper said several top Brotherhood leaders have been put under house arrest, though there was no immediate confirmation of which figures it was referring to. It also said arms caches allegedly belonging to the Brotherhood have been located.
Airport officials said screening departing passengers has been tightened to ensure leaders of the Brotherhood and other Islamist groups don't slip out with the help of sympathetic airport employees.
In a speech late Tuesday night, Morsi vowed not to step down and pledged to defend his legitimacy with his life in the face of the massive street protests.
Morsi demanded that the powerful armed forces withdraw their ultimatum, saying he rejected all "dictates" — from home or abroad. The army said if no agreement is reached between Morsi and the opposition it would intervene to implement a political road map of its own.
In his emotional, 46-minute address aired live to the nation late Tuesday, the Islamist leader accused loyalists of his ousted autocratic predecessor Hosni Mubarak of exploiting the wave of protests to topple his regime and thwart democracy.
"There is no substitute for legitimacy," said Morsi, at times angrily raising his voice, thrusting his fist in the air and pounding the podium. He warned that electoral and constitutional legitimacy "is the only guarantee against violence."
The speech showed that Morsi and the Muslim Brotherhood are prepared to run the risk of challenging the army. It also entrenches the lines of confrontation between his Islamist supporters and Egyptians angry over what they see as his efforts to impose control through the Brotherhood and his failures to deal with the country's multiple problems.
The Interior Ministry, in charge of the police, increased the pressure on Morsi. It pledged in a statement to stand by and protect the protesters against violence. "We are all the Egyptians, and at the face of the military, we are standing," they screamed.
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