On Sunday morning 10 Egyptian F16s flew low over Tahrir. The military was putting a third layer on to a cement wall barricading the presidential palace. A spokesman for the Salafist al-Nour party announced that "if Morsi is endangered or assassinated there will be an Islamist revolution for full Islamist rule in Egypt". An atmosphere of danger and crisis is being created. But it has never been the secular – left or liberal – forces in Egypt who have gone in for cold-blooded murder. If I were Morsi I'd watch my back.

President Morsi has been trying to please too many masters: his own Muslim Brotherhood, the other Islamists who find the Brotherhood not Islamist enough, the Americans, and the deep (or "thick" as the revolution calls it) state.

The demands of the revolution were clear: bread, freedom, social justice. Concerning "freedom", Morsi has refused to restructure the state's security apparatus; he appointed as interior minister the man who'd been Cairo's police chief in 2011 when protesters were massacred in the city's streets. People continue to be killed in jail and in police stations across the country.

Concerning the economy it's become clear that the Brotherhood's programme is basically Mubarak's: Morsi visited China accompanied by some of the biggest business allies of Mubarak; the banking communities talk of deals already being made by high-ranking officials and their relatives, and borrowing from the IMF and the World Bank is suddenly not sinful. Meanwhile, the president is able to issue the wildest constitutional declarations but is unable to make the smallest step towards establishing minimum and maximum wages.

So, his stance on security and the economy plays to the deep state and to the US. But most rank-and-file Islamists also want to see revolutionary change in economic ideology and security practices. How can he appease them? He throws them the bait that's the staple of every demagogue preacher: we'll clean up society, we'll rule through the word of God. We will write the constitution and anyone who rejects it is against the word of God.

And so to escape briefly from fulfilling promises of "freedom" and "social justice" the president invests himself with extraordinary powers to push through a referendum on a deeply flawed constitution. (He has now given up these powers but is still pushing the referendum through.)

It was expected that hundreds of thousands would protest. What was not expected was that they would be attacked by gangs of militia-style Muslim Brothers armed with sticks, clubs, knives and guns. Or that the Brotherhood platform would host a speaker who would say: our (Brotherhood) dead are in heaven, their (protester) dead are in hell. That the supreme guide would claim, on TV, that the bandaged young man in a poster behind him was a slain Muslim Brother when he was, in fact, Ahmad Feisal, an injured protester. Or that the Brotherhood would have groups in the morgue trying to appropriate the bodies of the murdered and give them Brotherhood funerals – as in the testimony of victim Muhammad al-Senussi's brother. A slain Muslim Brother is a martyr; a slain Muslim is a thug. And what about Karam Guirguis, an Egyptian Copt? [see response from Yusra Ghannouchi]

It is against this background of the president trying to appease an Islamist constituency and falsely appropriate the identity of the country that this struggle for the constitution needs to be seen.

A leader who wanted to unite the country would use our 1971 constitution until we got through this difficult time. But once again we have a presidency that would see Egyptians murdering Egyptians on the streets before it puts aside party politics and tries to lead honestly in the interests of the people.

If the revolution today says that Morsi has lost legitimacy, it is because his frail majority was born of sections of the revolution voting for him in order to keep out the military and the old regime. He has now betrayed them, and he now has blood on his hands.

The best minds in the Brotherhood have been steadily leaving the organisation as its non-inclusive policies have become more apparent, and as the degree of falsification and the number of volte-faces they make have become hard to stomach.

As I write, thousands of Islamists surround Media City – the home of the non-state TV channels. A video camera captures a huge bearded man pushing his hand against the mouth of a woman protester, Shahinda Meqled, a loved veteran of protest. In the video Shahinda pushes his hand away: we will not be silenced.

• This article was amended on 25 January 2013. The original stated that "the leadership of the Brotherhood would declare: our (Brotherhood) dead are in heaven, their (protester) dead are in hell." This has been corrected. In addition the author stated that the man pushing his hand against the mouth of a woman protester, Shahinda Meqled, is the "same man in a formal photograph in a semicircle gathered around the President". It is not the same man and the reference has been deleted.