CAIRO — Facing the most serious crisis of his presidency, Mohammed Morsi is leaning more closely than ever on his Islamist allies in the Muslim Brotherhood, betting on their political muscle to push through a decisive victory in the referendum on Egypt’s divisive draft constitution.
As tens of thousands chanted for his downfall or even imprisonment in a fourth day of protests outside the presidential palace, Morsi’s advisers and Brotherhood leaders acknowledged Friday that outside his core base of Islamist supporters he feels increasingly isolated in the political arena and even within his own government.
The Brotherhood ‘‘is who he can depend on,’’ said one person close to Morsi, speaking on the condition of anonymity to discuss internal deliberations. Morsi appeared to believe that he and the Brotherhood could deliver a strong vote for the draft constitution in next week’s referendum — strong enough to discredit the opposition, allow him a fresh start and restore some of his authority.
Struggling to quell protests and violence, Morsi appeared to offer a new concession to his opponents Friday by opening the door to a possible delay in the referendum on the draft constitution, now scheduled for Dec. 15, and even potential revisions by the Islamist-dominated constitutional assembly. But opposition leaders turned a deaf ear, reiterating their demands to begin an overhaul of the assembly itself.
‘‘He has to take these steps, and I hope that he listens to us,’’ Mohamed ElBaradei, the former UN diplomat and coordinator of the opposition, said Friday in televised response.
But Morsi’s advisers said he held out little hope of reaching a compromise and instead remained reliant on rallying his Islamist base, a strategy he displayed most vividly in a televised speech to the nation Thursday night. Addressing clashes between his Islamist supporters and their opponents that had killed at least six, Morsi all but declined to play the unifier, something he could have accomplished by sympathizing equally with those injured or killed on either side.
Instead, he struck the themes with the most resonance to his Islamist supporters, arguing that his backers outside the palace had come under attack by hired thugs paid with ‘‘black money’’ from a conspiracy of loyalists to the ousted president, Hosni Mubarak, and foreign interests determined to thwart the revolution. And he also said that some of the culprits had ‘‘direct links’’ to the political opposition, calling on Egyptians ‘‘to stand up to these heinous crimes.’’
Morsi’s turn back toward his Islamist base is a bet that the Brotherhood’s political machine can easily overcome even the reenergized secular opposition. And his advisers argue that the achievement of even an imperfect constitution will prove his commitment to the democratic rule of law and restore his credibility. But it also contributes to the paralyzing polarization now gripping Egyptian politics. It risks tarnishing both the constitution and Morsi as partisan and unable to represent all Egyptians. And it makes Morsi even more dependent on the same insular group that plucked him from anonymity and propelled him to the presidency.
The result could be a hollow victory that perpetuates the political transition’s instability.
‘‘OK, so you will have the referendum on Dec. 15 and you will end up with a ‘yes’ vote,’’ said Khaled Fahmy, a historian at the American University in Cairo. ‘‘On Dec. 16, Egypt will be infinitely more difficult to govern than it already is now.’’
Some senior Brotherhood leaders have acknowledged that the bruising battle may hurt their party’s fortunes in the next parliamentary elections, which are set for February if the constitution passes.
“I don’t think we will have the same level of trust, and I think our numbers will probably be affected,’’ one senior Brotherhood leader said Friday, speaking on condition of anonymity to discuss internal deliberations.
Morsi fears the Mubarak-appointed judges of the Egyptian judiciary, who have dissolved the elected Parliament and a first constituent assembly, and his attempt to put himself above its reach is what precipitated the current political crisis.
The military has said it will not take sides; its generals refused to submit to his authority until three months ago and secured their continued autonomy under the draft charter.