CAIRO (REUTERS) - Does Egypt face a new revolution? Millions hope so, it seems; they have signed a national petition demanding the president resign and plan to take to the streets on June 30, when Mr Mohamed Mursi marks a year in office.

Their slogan is a call for revolt: "Tamarud - Rebel!" But for all the simmering discontent with the Islamist who has presided over political and economic paralysis, millions more are ready to defend Egypt's first freely elected leader; they say those campaigning for him to quit are agents of the old regime and plan their own pro-Mursi rallies starting on Friday.

Their counter-campaign - "Tagarud" - calls for open minds.

There is a risk of more of the violence that has punctuated the two and a half years since Mr Hosni Mubarak was toppled by a blast of rage from Tahrir Square. "June 30" crops up endlessly in conversation. The Cairo bourse has shrivelled in anticipation and security forces say they are preparing to deal with trouble.

"There is a strong chance of violence," said retired general Sameh Seif al-Yazal. "It could start from any side."

It is unclear what can end stalemate between the Islamists, whose organised electoral base has handed them the formal levers of power, and a diffuse opposition of liberals, Christians and secular conservatives united in fear of Islamic rule, plus a mass of the uncommitted, fed up with economic drift under Mr Mursi.

The "culture war" between elected Islamists and a secular opposition, with a once-political army in the background, has echoes of today's unrest in Turkey, but deep economic crisis and a still unformed political system makes Egypt much more fragile.

With world powers at odds over Syria, where Mr Mursi has backed the Sunni Muslim revolt, and Washington funding an Egyptian army that honours Cairo's peace treaty with Israel, any instability in the most populous Arab state has implications far beyond.

The wealthy generals, once led by Mr Mubarak but who sacrificed him to save themselves, have said they want no more political role. Islamists say it would mean civil war if the troops moved against them. Yet the army is still held in high regard by the vast majority and says it will intervene to maintain order.

However June 30 ends - and few will bet with confidence on the outcome - it will help determine whether the Arab Spring eventually blossoms, or withers - not just for 84 million Egyptians but for would-be democracies across the Middle East.

UNFINISHED REVOLUTION

"This revolution is not over yet," said Mr Mohamed ElBaradei, a former top United Nations diplomat and one of the best known faces of Tamarud, whose keen young sidewalk volunteers say their petition is close to gathering more signatures for Mr Mursi's - hypothetical - removal than the 13 million votes that elected him a year ago.

Mr ElBaradei spoke at a two-week-old sit-in by artists at the Culture Ministry. It was prompted by the new minister firing the head of Cairo Opera and by fears of a new puritanism after an Islamist lawmaker urged a ban on ballet, calling it "naked art".

Such threats grip the liberal media and Mr ElBaradei said Islamist dominance must be stopped: "We ask every Egyptian to go out on the 30th, to free ourselves and reclaim our revolution."

For the millions of poor, for whom the ballet ranks low in their priorities, it is an economy caught in a vice of collapsed tourist income, rising world commodity prices and a growing population dependent on subsidised bread and fuel that matters.

"We don't want Mursi. We want change," said Ms Umm Sultan, working with her son at the family juice stall in Cairo's Old City. "They must give us money so our children can live."

Echoing fellow Islamists governing in Turkey, Mr Mursi's Muslim Brotherhood insists he has a democratic mandate and warn that protest is permitted - "a healthy sign that this revolution has actually worked", one aide called it - but must be peaceful.

Mr Mursi himself says he will react "fiercely" to trouble from "felloul" - "remnants" of Mubarak - and calls the petition, which has no legal weight, "an absurd and illegitimate action".

The interior minister said in a television interview on Monday that during the demonstrations the ministry would only be involved to protect citizens if clashes take place or public property is harmed. He called on Islamist supporters to avoid taking to the streets on June 30 during the opposition demonstrations.

"I still tell the Islamist faction that there is no need to be on the streets on the 30th. If this happens and friction takes place, we will be in a very difficult situation and will be in a state of battle like, let's say, nearby countries," Minister Mohamed Ibrahim told CBC channel late on Monday.

Mr Ibrahim added that the ministry would close all the Sinai peninsula border crossings along the Suez Canal during the demonstrations to prevent people coming from outside.

There have been scuffles this month between groups gathering signatures; an apartment used by Tamarud was firebombed. A new test looms this Friday, when Islamists plan pro-Mursi rallies.

The heart of the problem is a failure to build consensus.

With opponents in disarray, the Brotherhood and its allies won majorities in both houses of parliament and the presidency last year and rushed a constitution through a referendum. The opposition, partly backed by a judiciary the Islamists see as Mubarak holdovers, now reject most of those state institutions.

Elections for a new lower house that might provide a forum for national dialogue are being held up by rows over the rules.

Anchoring his power in the provinces, Mr Mursi named Islamists to run several governorates on Sunday, including one from a group whose gunmen massacred 58 foreigners in Luxor and will now head the administration in the temple city, a hub for tourism.

But, lacking broad popular support, the legislature and the executive have struggled to act decisively on an economy being kept afloat by soft loans from Qatar and other regional allies.

ISLAMISTS WARN ARMY

There seems little prospect the Tamarud petition will induce Mr Mursi to resign - and even some liberal commentators say that might set an unwelcome precedent. Mr Mursi's win seemed fair and a new presidential vote might produce a broadly similar result.

Yet a Zogby poll on Monday showed only 28 per cent of voters now see his election as positive or at least an outcome to be respected - down from 57 per cent a year ago.

The poll also showed, however, that no current opponent is clearly more popular than the bespectacled, bearded face crossed out with a red "X" on Tamarud's ubiquitous posters.

But if the protest movement seems like a leap into the unknown, that is not deterring large numbers from joining it.

"Tamarud is a representative public reaction to the Muslim Brotherhood and Mr Mursi's failure to run the state," said Mr Hassan Nafaa, a Cairo University political scientist who says Mr Mursi must resign for his "stupidity".

"It has left people no option but the streets and so they will come out - in large numbers."

The president's allies will not give in so easily: "If Mursi ends up being ousted by violence or a coup by the army or police, there will be an Islamic revolution," said Mr Al-Ghaddafi Abdel Razek, manager of the pro-Mursi Tagarud campaign which he said had collected 7 million signatures backing Mr Mursi.

"We have our people in the army and the police, too, and we are ready," added Mr Abdel Razek, 37, a pharmacist once jailed for his membership of militant group al-Gamaa al-Islamiya.

"We know that if Mursi goes, we'll all be in prison."

DECISION TIME

Over at the opposition campaign, spokesman Mahmoud Badr is grappling with piles of signatures and ID numbers that need to be verified against databases if Tamarud is to make the case it hopes to the United Nations that its petition is genuine.

Even without international intervention, Mr Badr argued, the weight of opinion could embarrass Mr Mursi into stepping aside.

Others say that at least it might push him to listen to them.

"It is a new factor, this kind of mobilising effort with the numbers of folks involved," said United States pollster James Zogby. "We don't know where it's going, but we're clearly turning a page.

"This is a revolution still to be resolved."

And if Mr Mursi goes? It seems hypothetical now, but Mr Badr and his team have a post-Mursi plan: the constitutional court chief would be interim head of state with a small technocrat cabinet.

For many, exasperated by power cuts, shortage of fuel and rising prices, a return to army rule would be welcome - though the military insists it wants no such responsibility. Its chief, appointed by Mr Mursi, has urged "a framework for consensus".

One military source told Reuters the army was ready for all eventualities after June 30 - "but we will not interfere unless the situation seems to be heading towards violent conflict".

Army chief Abdel Fattah al-Sisi has said troops will "defend the state and what is sacred to the people" - that, the source said, included their rights to protest.

As the rallies approach, Egyptians have decisions to make.

Mr Ahmed Mahmoud, 30, a labourer from Alexandria is already in the capital to make his voice heard: "I want to tell Mursi loud and clear he needs to go since he has failed to meet the demands of our revolution, for a better life and freedom," he said. "We are tired and cannot take it any more. We want to live."

But others, who fear yet more unrest can only plunge them deeper into poverty, are more patient. Mr Mohamed Ali, 26, a waiter at a Cairo cafe, said Mr Mursi should be given his chance: "We are new to democracy and we should give him time to work and learn."