A street vendor stands on a pedestrian crossing in front of an army guard closing off the road ahead, that leads to the presidential palace, in Cairo Dec. 18, 2012. Opponents of Egyptian President Mohamed Morsi staged protests in Cairo on Tuesday against an Islamist-backed draft constitution that has divided Egypt but looks set to be approved in the second half of a referendum this weekend. (MOHAMED ABD EL GHANY/REUTERS)

An opposition appeal for mass protests against a draft Egyptian constitution backfired Tuesday, with a dismal turnout forcing leaders to acknowledge that they erred in calling their supporters to the streets.

“We confused our people today,” said Hussein Abdel Ghany, a spokesman for the main opposition bloc, the National Salvation Front, as hundreds of dejected demonstrators headed home. “This was a mistake. We have to admit it.”

The failed rally suggested the waning power of protests after two years of nearly nonstop demonstrations that began with the exhilaration of an 18-day revolution, but that have since devolved into bitter infighting among former allies. The lackluster turnout also pointed to difficult choices ahead for the loosely organized group of liberals, leftists, seculars and Christians who oppose President Mohamed Morsi and his Muslim Brotherhood backers.

Tuesday’s demonstration came in between two rounds of voting on a referendum that appears headed for passage, and that would give Egypt a new constitution. The first round was backed by approximately 57 percent of voters, according to tallies by the Brotherhood that have proved accurate in the past. The second round, scheduled for Saturday, is expected to yield a wider margin in favor of the document, which has received strong support from Morsi and other Islamist leaders.

The opposition had alleged widespread fraud during the first round of voting, but provided little evidence. Egypt’s Justice Ministry said Tuesday it would investigate claims of voter irregularities.

The weeks leading up to the vote were a maelstrom of violent protests, legal standoffs and extraordinary moves by Morsi as he maneuvered to put the new constitution in front of voters. He and his allies have argued the document will bring stability to Egypt, while detractors say it will lead to a far more religiously orthodox state that will limit the rights of women and minorities.

Many of those who gathered outside the presidential palace for protests Tuesday night predicted dire consequences for the nation if Morsi prevails.

“We had a revolution because we were being run by a group of terrorists and thugs. And now they’ve been replaced by a group with the same mentality,” said Mohammed Maged, a 32-year-old lawyer.

Nearby, a protest leader chanted “No to the Brotherhood’s constitution!”

But his calls were answered meekly, and for much of the night, silence reigned, except for the occasional whimper of a bedraggled horn. Vendors who have come to recognize protests as a good business opportunity steered their horses home, their carts still laden with unsold bread, bananas and colas.

On a 63-degree night with clear skies and no wind, one protester speculated hopefully that the winter chill had kept people home.

Or maybe, he said, “the people just got bored with coming out to the streets.”