Huge demonstrations are underway once again in Cairo and across Egypt, as the country slips again into political crisis. Here is a look at the issues that are driving the protests and what could happen next.

Why are Egyptians protesting again?

Since the end of former president Hosni Mubarak’s 30-year rule during the Arab Spring uprisings more than two years ago, Egypt has remained in turmoil.

Much of the country’s anger has centred on Egypt’s dismal economy, which has been in crisis as the country has watched its vital tourism industry dry up over the last two years. Power outages have become frequent, and food prices have been soaring, even as unemployment has grown.

At the same time, many liberals have accused president Mohammed Morsi of betraying the revolution by trying to “Islamize” their relatively moderate country.

They have looked suspiciously upon the appointment to cabinet of members of the powerful Muslim Brotherhood, the Islamist group that was once suppressed under the Mubarak regime but that has since become Egypt's strongest political force.

Discontent with Morsi’s rule turned to anger in November 2012, when the president unilaterally issued a constitutional declaration giving himself extensive powers, protecting his decisions from judicial review and barring the courts from dissolving the assembly and houses of parliament. That move sparked days of protests, and led to the first calls for Morsi to leave.

The anger has since been aggravated by further appointments of Muslim Brotherhood members to key posts -- appointments that liberals say were based not on competence but on loyalty to Morsi.

What has happened in recent days?

On Sunday -- the first anniversary of Morsi’s inauguration -- millions of Egyptians took to the streets in Cairo and other cities, calling for Morsi to step down. The demonstrations have been the largest in the country since Egyptians rose up against Mubarak in January 2011 and have remained largely peaceful, given their size. But at least 16 people have died and hundreds more were injured in sporadic clashes, most of them in Cairo.

Then on Monday, Egypt's powerful military issued a "last-chance" ultimatum over state TV, giving Morsi 48 hours to meet the demands of the protesters, or watch the army intervene and impose its own plan for the country.

Two of Morsi's spokesmen and his foreign minister have since resigned.

Who are the protesters?

The protests have not been led by any one political party, but by the Tamarod, which means “rebellion” in English. The grassroots movement was established in early May by young Egyptians, including members of the Egyptian Movement for Change, also known as Kefaya, which pushed for political reform under former president Mubarak in 2004 and 2005.

What do the protesters want?

The key demand has been their call for an early presidential election. They say they have collected more than 22 million signatures both online and in paper demanding the president resign.

If Morsi steps down, the Tamarod wants to see head of the Supreme Constitutional Court become interim president. They then want a new constitution drafted to replace the one created last year, and new presidential elections held within six months.

What are Morsi's options?

Morsi's office has issued a defiant statement insisting that a "modern democratic state" was one of the main achievements of the anti-Mubarak revolution, and that Egypt should not allow itself to take a step backward.

But with the resignation of several key ministers in the last week, the liberal opposition declining to work with Morsi, and Egyptian police refusing even to protect the offices of the Muslim Brotherhood, Morsi’s current government likely can no longer function as is, observers say.

He has the option of reshuffling his cabinet, holding a referendum on completing his term, or calling an early presidential election, as the protesters are demanding.If Morsi chooses to step aside, his prime minister, Hesham Qandil, could take over his role until a new president is elected.

With reports from The Associated Press