CAIRO — With the passage of a divisive constitution, Egypt’s Islamist leadership has secured its tightest grip on power since Hosni Mubarak’s ouster nearly two years ago and laid the foundation for legislation to create a more religious state.

The opposition’s response — a vow to keep fighting the charter and the program of Islamist President Mohammed Morsi — ensured that the turmoil of the past two years will not end as many, especially the tens of millions of poor craving stability, had fervently hoped.  

“The referendum is not the end game. It is only a battle in this long struggle for the future of Egypt,” the opposition National Salvation Front said in a strongly worded statement on Sunday.

“We will not allow a change to the identity of Egypt or the return of the age of tyranny,” added the front, which claims the new constitution seeks to enshrine Islamic rule in Egypt and accuses the Islamists of trying to monopolize power.

Critics say the new constitution does not sufficiently protect the rights of women and minority groups and empowers Muslim clerics by giving them a say over legislation. Some articles were also seen as tailored to get rid of Islamists’ enemies and undermine the freedom of labor unions.

Morsi’s Muslim Brotherhood, Egypt’s most powerful political organization in the post-Mubarak era, claimed early Sunday that the charter it had backed was approved in the two-stage vote with a 64 percent “yes” vote overall. Though official results will not be announced until Monday, there is little doubt they will confirm the passage.

Once the official result is out, Morsi is expected to call for a new election of parliament’s lawmaking lower house within two months.

And if all of the elections since Mubarak’s February 2011 ouster are any predictor, Islamists will again emerge dominant. In the last parliamentary vote in late 2011, the Muslim Brotherhood and its allies the Salafis — ultraconservative Islamists — won about 70 percent of seats.

If Islamists win the overwhelming majority again, there is nothing to stop their lawmakers from legislating in support of their longtime goal of turning Egypt into an Islamic state. The Salafis will likely seek to enlist the support of the less radical Brotherhood for legislation that would nudge Egypt closer to a religious state.

Khalil el-Anani, a British-based expert on Islamic groups, said the Salafis are likely to insist that every piece of legislation conforms with Islamic Shariah law, especially with regard to questions of morality, culture, personal freedoms and the nation’s identity.

“The Salafis will want the Brotherhood to reward them for their campaigning for the ‘yes’ vote,” said el-Anani. “The Brotherhood, meanwhile, will want to rebuild their image as a credible democratic group after a period in which it seemed in complete alignment with the Salafis.”

The Islamists could also move early to pass laws restricting vibrant and outspoken privately owned media organizations that have flourished since the uprising and reported critically on Morsi and the Brotherhood.

Egypt analyst Michael W. Hanna said, however, that enduring political tensions will make it difficult for the Islamists to push ahead with any major or sensitive legislation.

“There will be a huge domestic backlash to any unpopular legislation, especially when it comes to the economy or the media,” said Hanna of New York’s Century Foundation.

Until the lower house is elected and seated, parliament’s upper chamber, the Shura Council, will temporarily assume legislative powers and may give priority to more pressing issues.

After the opposition brought hundreds of thousands of protesters to the streets in the past four weeks, including tens of thousands outside Morsi’s presidential palace in Cairo, the Shura Council is expected to hurriedly debate and vote on a legislation that would place tight restrictions on the right to demonstrate.

More serious challenges to Morsi’s leadership may lie ahead. The millions who voted “yes” for the constitution are hoping for stability, jobs and business opportunities that may be slow in coming.

The president will soon have to introduce painful economic reforms to salvage a deal with the International Monetary Fund for a $4.8 billion loan that was delayed at Egypt’s request because of the political turmoil of the past month.

A glimpse of what may be in store on that front emerged Sunday after Prime Minister Hesham Knadil met with the Cabinet’s economic team.

“The current financial and economic situation is in grave danger,” said Cabinet spokesman Alaa el-Hadidy. “Leaving things the way they are is not something we can afford to do,” he said, hinting at the necessity of structural reforms. These will include price and tax hikes as well as lifting subsidies on fuel.

Morsi recently rescinded a package of price and tax hikes hours after he decreed them, saying he did not want to burden poor Egyptians with a higher cost of living. But economists say it is only a question of time before the package is re-introduced.

With foreign currency reserves around half of what they were two years ago and tourism revenues hard hit by resurgent political turmoil, the economy has been in a free-fall for months. Deepening the nation’s economic plight is the seemingly endless series of strikes and demands for salary increases and better benefits.

Price hikes, warn many analysts, could prove to be the last straw for the nearly half of Egypt’s 85 million people who live around the poverty line of surviving on $2 a day.

Many Egyptians want to see Morsi’s government moving aggressively to tackle the nation’s pressing problems such as security and reviving the vital tourism sector.

“We want factories to work again so we can find jobs here instead of traveling abroad to find work,” said Mohammed Sweilam, a metal worker who spent seven years working in oil-rich Saudi Arabia. “When stability prevails, I will consider coming home to stay. Let us give the Brotherhood a chance. We owe them this,” he said as he waited in line on Saturday to cast his vote in the town of El-Saf in Cairo’s neighboring Giza province.

Another pressing issue for the new legislators may be the anti-Islamist editorial policy of the independent media, particularly privately owned TV networks whose political talk shows are watched nightly by millions and shape public perceptions.

Already, Morsi’s allies have been filing numerous complaints against media celebrities who criticize or mock the president and the Brotherhood, including hosts of satirical shows and newspaper columnists. Several of them are on trial or being investigated on charges of “insulting” the president or undermining national security.

Since Morsi took office nearly six months ago, Brotherhood members or sympathizers have been named editors of most of the roughly 50 state-owned publications. The powerful information minister is a prominent Brotherhood leader.

A recent court ruling also shut down a TV network whose owner is a harsh critic of Morsi. Salafis who support Morsi have been staging a sit-in outside a media complex in Cairo for weeks to protest against what they say is the anti-Islamist policies of private TV networks housed there.

The constitutional crisis has re-energized and united the once-fractured opposition, turning it into a force to be reckoned with in the fight over Egypt’s future. In a sign of its newly found strength, the National Salvation Front, the main opposition group, on Sunday scornfully rejected a Brotherhood invitation for dialogue.

The opposition has dismissed the constitution as the fruition of an illegitimate process.

The low turnout for the referendum — 32 percent of the more than 51 million eligible voters, or 20 percent of Egypt’s 85 million people, according to unofficial results — has shown the limitations Islamists face in marketing an Islamic state in a nation still largely loyal to secular traditions.

Morsi could be tainted by allegations of voting violations instigated by Islamists and reported by rights groups. The charges could cast doubt on the democratic credentials of the Islamists and lead to damaging analogies between Morsi’s administration and Mubarak’s authoritarian regime, which oversaw massive electoral fraud for years.

The opposition is demanding an investigation of alleged wrongdoing in the vote.

The Brotherhood insisted violations were limited and should not affect the referendum’s integrity.

But prominent lawyer and rights activist Negad Borai described the violations as systematic.

“What happened in the referendum could lead to violence and bloodshed if repeated in a parliamentary election when the stakes are higher,” he warned.