EGYPTIAN PRESIDENT Mohamed Morsi sounds plausible in claiming he is not attempting to establish an Islamic dictatorship. The Muslim Brotherhood nominee, who won a two-round free election this year, issued a sweeping decree last week exempting his decisions from court review — thereby giving him more power than ever wielded by Hosni Mubarak, or any other modern Egyptian ruler. Yet his main aim appeared to be to block reactionary judges from dissolving an assembly now writing a new constitution. Having already dismissed a democratically elected parliament on a technicality, the Mubarak-appointed Supreme Court was threatening to derail the long-delayed transition to a new political system and, perhaps, to tip the country back toward chaos.

Yet Mr. Morsi’s reaction was a huge overreach — as he appeared to recognize Monday after facing a tumultuous weekend of demonstrations. After meeting with the Supreme Judicial Council, which oversees the justice system, the president was said to have agreed that his immunity would extend only to “sovereign matters,” a vague term that nevertheless implied a willingness to accept court checks on most government activity. Mr. Morsi’s original decree says he will retain his exceptional powers only until a new constitution is approved and a new parliament elected — which could take until the middle of next year.

That’s not likely to be the end of the matter. If Mr. Morsi is not the Islamic Lenin of his opponents’ imagining, neither is he or his party leading the country toward the full democracy they have promised. Having amassed more than two-thirds of the vote in the first elections after Egypt’s 2011 revolution, the Muslim Brotherhood and more conservative Islamists dominate the constitutional assembly and have made little effort to compromise with opponents. At last count, 22 of the assembly’s 100 members had resigned, all of them leading liberals or Christians. They say the Islamists are preparing a document that strengthens the role of Islamic law in Egypt’s domestic legislation, weakens protections for women and opens the way to new restrictions on media freedom.

Mr. Morsi’s defenders argue, with some justice, that the liberals have also been uncompromising. But if it is to avoid further turmoil, the government must take the lead in forging a consensus with its opponents, rather than attempting to overpower them. To do that, the Brotherhood must agree to a constitution that preserves legal space for secular society and non-Muslims, avoids repression of women, preserves free speech and ensures that free and fair elections can take place in the future.

That is where the United States should come in. With a badly needed International Monetary Fund loan pending along with a bilateral debt- forgiveness deal, the Obama administration has considerable leverage over the Morsi government. President Obama spoke to Mr. Morsi several times during last week’s Gaza crisis, which ended with a cease-fire that the United States sought and Egypt helped to broker. Now Mr. Obama must make clear that Egypt’s relations with the United States depend not only on such strategic cooperation but also on the creation of a political system that meets basic tests of democracy and respect for human rights.