LONDON — President Mohamed Morsi of Egypt has made a big blunder. His motives may have been honorable — I am inclined to give him the benefit of the doubt — but the error is grave and needs to be rectified.
His seizure through decree of near absolute power, placing him above judicial oversight, recalls the famous phrase of the French diplomat Talleyrand: “Worse than a crime, it was a mistake.”

Morsi says his move is temporary — a means to fast-forward Egypt out of its post-revolutionary limbo — but “temporary” is not a credible word in a nation where the ousted President Hosni Mubarak’s “emergency” dictatorial powers lasted decades.

The constitution of the most important Arab state — home to almost 25 percent of the world’s Arabs, the litmus test of the freedoms promised by the Arab Spring — cannot be forced through by a constitutional assembly that has lost about a quarter of its 100 members, mainly liberals and women who have walked out in protest. It now amounts to a discredited rump body dominated by parties of Islamist inspiration.

Not when the nation’s judges (who would have to supervise an eventual referendum on a draft constitution) have gone on strike and Morsi through his rashness has accomplished a singular political feat: Uniting Egypt’s ineffective and divided liberal-secular factions in mass street protests and a demand that the decree be revoked. A tweet from Mohamed ElBaradei, the Egyptian Nobel laureate, comparing Morsi to a new Pharaoh has resonated.

Morsi must press the reset button. Democratic politics is laborious; ask President Obama. He cannot avoid difficult political trading in an Egypt where he won the presidential election this year with 51.7 percent of the vote. The other 48.3 percent cannot be trampled upon. At a minimum his decree must be undone and the constitutional assembly given the credibility only inclusiveness can confer.

I said I was inclined to give Morsi the benefit of the doubt on his motives. He knows dictatorship will not fly in the new Egypt. He outmaneuvered the military, helped on Gaza, was brave on Iran and Syria. He is a product of a Muslim Brotherhood culture that, as a result of fierce repression, inclined toward the conspiratorial and secretive. Enemies were everywhere.

It is easy to see how, with a court decision looming Sunday that might dissolve the constitutional assembly, Morsi would have convinced himself of an ancien-régime plot to undermine popular will and put Egypt back at square one in its transition. The problem is he did not try to resolve the issue by reaching out. He closed himself in an absolutist cocoon and has allowed voting on the draft to begin.

In a recent interview in Cairo, Essam Soltan, a prominent lawyer who was a member of the Brotherhood and left to form his own party, told me: “Morsi represents the will of the people. Still you must remember he comes from a movement with 60 years of being forced underground. This produces diseases; wild generalizations like seeing everyone as the enemy of religion.

“Interests and human ideas should be the basis for discussion, not religion. But the left and liberals also have problems. Their ideas came from outside rather than within an Egyptian democratic system.”

Plenty of liberals these days in Egypt are inclined to reduce liberty to a subordinate clause. Yes, they say, we are free to say what we like, write what we like, and that’s dandy, but we cannot abide the Muslim Brotherhood and oppose whatever they do. To which I would say freedom is not a parenthesis. And 51.7 percent in a democracy is enough to govern.

Egypt has traveled a long way: U.S.-trained generals have saluted a freely elected Brotherhood president and a proud nation has emerged from a crippling political deep freeze. But the achievements are fragile.

Morsi and his liberal opposition would do well to recall Benjamin Franklin’s words on emerging from the Constitutional Convention in Philadelphia and being asked what system of government had been adopted: “A Republic, if you can keep it.”

Keeping Egypt’s newfound freedom will take courage and compromise. Morsi must correct his mistake and Obama should work hard behind the scenes to ensure that. Liberals must come together and accept trade-offs.

The draft constitution fails Egypt by favoring the Islamic camp, but the problems are not insurmountable. Since I wrote about it last month, a controversial clause that said men and women have equal rights “insofar as this does not conflict with the rulings of Islamic Shariah” has been dropped. This is important.

A broad compromise alluding to the “principles” of Islamic law as a guiding reference, as in the current Constitution, seemed to have been reached earlier this month but disintegrated as Islamists tried to rush through the draft document, whose concentration of power in the presidency is worrying.

Railroading a document of this importance is not an option. Egypt will split, investment dry up and unrest continue. Morsi must overcome his Brotherhood suspicions to forge a credible constitutional assembly including liberal opponents who, like Republicans in Congress, should now express patriotism through pragmatism.

A free Egypt, the first, is worth keeping. It could be a core agent of change in a region that desperately needs new thinking.