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Egyptians start voting Tuesday on a draft for their country's next constitution, a vision for the nation's future and a milestone in a military-backed roadmap put in place after Mohammed Morsi was overthrown in a coup last July.

The two-day balloting is also widely seen as a referendum on a likely presidential run by Egypt's top general — but held in a climate of fear and intimidation.

It's also the first test at the ballot box for the popularly backed coup that ousted the Islamist Morsi and his Muslim Brotherhood. A comfortable "yes" vote and a respectable turnout would bestow legitimacy on the cascade of events that followed the coup while undermining the Islamists' argument that Morsi remains the nation's elected president.

Morsi's Brotherhood, which is now branded as a terrorist group, has called for a boycott of the vote. Morsi himself is facing three separate trials on charges that carry the death penalty.

An astounding 160,000 soldiers and 200,000 policemen are to deploy across Egypt to guard polling stations and voters on Tuesday and Wednesday.

The unprecedented security follows months of violence that authorities have blamed on Islamic militants. In the six months since Morsi's ouster, there has been an assassination attempt on the interior minister as well as deadly attacks on key security officers, soldiers, policemen and provincial security and military intelligence headquarters.

Morsi's supporters have said they would stage massive demonstrations and have labeled the draft charter a "constitution of blood." In response, the government has warned it would deal harshly with anyone interfering with the referendum.

In the days running up to the vote, Egypt looked more like a country going to war rather than one preparing for a transition to democratic rule. The government and the overwhelmingly pro-military media have portrayed the balloting as the key to the nation's security and stability over which there can be no dissent.

Hundreds of thousands of fliers, posters, banners and billboards exhort Egyptians to vote "yes." Posters — and campaigns — urging a 'no' vote have led to arrests.

The referendum is the sixth nationwide vote since the authoritarian Hosni Mubarak was ousted in a popular uprising in 2011, with the five others possibly the freest ever seen in Egypt.

While unlikely to be stained by fraud, the vote is taking place at a time when many of the freedoms won in the uprising that toppled Mubarak have vanished in the months since Morsi was removed after just one year in office.

The new charter, drafted by a liberal-dominated committee appointed by the military-backed government, would ban political parties based on religion, give women equal rights and protect the status of minority Christians. But it also gives the military special status by allowing it to select its own candidate for the job of defense minister for the next eight years and empowering it to bring civilians before military tribunals.

The charter is in fact a heavily amended version of a constitution written by Morsi's Islamist allies and ratified in December 2012 with some 64 percent of the vote but with a nationwide turnout of just over 30 percent.

A big "yes" vote would also provide a popular mandate for the military chief, Gen. Abdel-Fattah el-Sissi, to run for president in elections later this year. El-Sissi has yet to say outright whether he plans to seek the nation's highest office, but his candidacy appears increasingly likely every day.