Egypt’s fractious opposition urged its supporters Wednesday to vote “no” on a contentious Islamist-backed draft constitution but left open the possibility of boycotting Saturday’s vote altogether if several conditions were not met.

Hamdeen Sabahi, a leader of the opposition National Salvation Front, called the charter “distorted and flawed and lacking the most important condition, which is national agreement.”

“For this, the Front has decided to call for Egyptians to go to the polls and vote ‘no,’ ” Sabahi said at a news conference.

But the decision — coming just three days before voting begins in Egypt — will probably have little practical impact on the street, according to analysts, who say the opposition is vastly out-
organized by President Mohamed Morsi’s powerful Muslim Brotherhood supporters.

The referendum, which is already underway for Egyptians living abroad and will begin Saturday for the 51 million eligible voters inside the country, comes amid legal chaos, with the judiciary as divided as the country itself.

In Egypt, judges are required to supervise ballot boxes during elections and referendums — which means that every ballot box must be under the constant observation of judges during the voting process.

At the moment, however, some of the country’s most powerful judicial organizations have sided with the opposition and have refused to help supervise the referendum, citing what they consider to be an array of legal problems with the way Morsi and his Islamist supporters approved the draft charter and called for the vote. Other judges have sided with Morsi and agreed to supervise the vote, and it remains to be seen how many sign up for duty Saturday.

Anticipating a shortage, Egypt’s electoral commission said early Wednesday that voting would take place on two consecutive Saturdays. Ten provinces, including Cairo and most urban areas, will vote Saturday, and the rest will vote Dec. 22, although that decision may be legally challenged. An election law requires that the referendum be held within 15 days of the approval of the charter by the assembly that drafted it; the second Saturday would stretch beyond that time frame.

In its statement, the National Salvation Front outlined four conditions that must be met to avoid a boycott by its supporters, including that the referendum be completed in one day. The other terms include providing for security at polling places, a prompt reading of vote tallies and the presence of international observers.

The process of drafting Egypt’s new charter and the document itself have revealed a profound gulf in how Egypt’s revolutionaries see themselves and their future, with Islamists on one side and a loose alliance of liberals, secularists, Christians and figures from the ousted regime of Hosni Mubarak on the other.

Attempts in recent days to bridge the sizable divide have failed.

Opposition leaders, including Nobel Peace Prize winner Mohamed ElBaradei, refused to take part in a “national dialogue” Morsi called last week to solve the political crisis. An attempt by the head of the military to bring an array of Egyptians together for talks Wednesday was postponed indefinitely because of low attendance. In rival street protests over the past two weeks, each side has called the other illegitimate.

Sharaf al-Hourani and Ingy Hassieb contributed to this report.