(CNN) -- Egyptians took to the polls Saturday to give their thumbs-up or thumbs-down to a controversial draft constitution that has had opposition protesters up in arms and on the streets for weeks.
The path to the referendum has been marred by violent incidents on both sides as well as extensive institutional and political power struggles, and President Mohamed Morsy and his allies have rushed the document to a popular vote.
Morsy, who himself has been the object of raucous mass opposition protests as well as mass demonstrations of support, cast his ballot early Saturday in the Cairo suburb of Heliopolis, according to state-run news agency MENA.
Sentiments about the national charter have been split down the same political lines of those who support the president and those who oppose him and have been equally as heated.
Those opposed to it feel it contains subtle wording that limits rights and gives too much political power to religious figures and institutions.
Many in the opposition called earlier for a boycott of the referendum, but most have swung around to urging citizens to turn out and vote "no."
Liberal oppositionist Mohamed ElBaradei -- better known globally than in his native Egypt due to his former role as head of the International Atomic Energy Agency -- is one of them.
"To every Egyptian -- male and female: Listen to the voice of reason and conscience. Vote 'no' in order to save Egypt and support the nation," he tweeted Saturday morning in Arabic to fellow Egyptians.
He later tweeted in English, "Adoption of divisive draft constitution that violates universal values & freedoms is a sure way to institutionalize instability & turmoil."
Former presidential candidate and prominent opposition leader Hamdeen Sabahy called for a "no" from his followers in a tweet Saturday: "We deserve a constitution that is worthy of the revolution and the dignity of its martyrs."
Supporters of the draft constitution herald what they say is its protection of personal rights, especially its provisions on handling of detainees in the judicial system, which made capricious use of its powers under deposed autocratic president Hosni Mubarak.
Dr. Esam al-Erian, Morsy's adviser and deputy head of the Islamist Freedom and Justice Party said on his party's Facebook page: "Holding the referendum marks a new phase in Egypt's history. It ends hopes of those wishing for Mubarak's return."
Hassan el-Shafie, a senior cleric and member of the Constituent Assembly that drafted the constitution, called opposition to the document "purely political," saying the highest Islamic institution in the land "has made it ultimately clear that the country must be a modern democratic nation."
International rights group Human Rights Watch says the draft constitution "protects some rights but undermines others." It "fails to end military trials of civilians or to protect freedom of expression and religion," it said in a statement.
Egypt's Christian leaders have neither come out for or against the constitution, but instead encouraged believers to vote their own conscience.
Though election observers are officially allowed, rights organizations have criticized the lack of real monitoring possibilities, and well-known international observer teams have not announced their participation.
A group of 21 Egyptian human rights organizations accused the government body responsible for monitoring of bias and manipulation in a statement released Thursday.
"Currently, the NCHR (National Council for Human Rights) is attempting to monopolize civil society's efforts to monitor the referendum, despite the fact that the council lacks impartiality," the group wrote. They accuse the body of being stacked with Mosry supporters who participated in drafting the constitution.
The Carter Center, which has sent 140 witnesses to observe Egyptian elections in the past, declined to send a delegation to observe the referendum.
"The late release of regulations for accreditation of witnesses precludes the Center from conducting a comprehensive assessment of all aspects of the referendum process, consistent with its methodology for professional observation of elections," the center said in a statement Thursday.
Other international organizations known for monitoring polls, the OECD and the United Nations, have not posted announcements they would participate.
Polling in the referendum is split between two days.
Over 6500 stations will welcome up to 26 million eligible voters in the first round of balloting, with the military and police working together to ensure security and proper procedure, MENA said.
Ten provinces, including the highly populous ones of Cairo and Alexandria, vote until 9:00 p.m. Saturday, MENA reported, after having opened at 8:00 a.m. Seventeen more provinces vote in a week on December 22, rounding out the referendum.
Long lines of voters cued up ahead of poll openings, and turnout has been high, the electoral commission said, leading it to extend voting by two hours. It was originally scheduled to end at 7 p.m. Polling has gone smoothly so far, according to the election commission.
The rocky road to the referendum began when judges threatened to shut down the assembly tasked with drafting the constitution. President Morsy then issued an edict in late November declaring all of his past and present decisions immune from judicial review until the holding of the constitutional referendum.
He also sacked the head of the judiciary. The judicial system has many in its ranks who are loyal to former autocratic President Hosni Mubarak.
The Islamist president's opposition saw the exceptional move as a grab for dictatorial powers and poured into the streets, converting Tahrir Square in central Cairo back into a the center of public discontent it had been during the uprising that brought down Mubarak.
The president has since dropped his provocative decree going forward, but the situation has remained tense, and violence has continued.
In response to violent clashes, Morsy has given the military the authority to make arrests during the electoral run-up.
Morsy's Islamist allies rushed the drafting of the constitution to completion, which some saw as a tactic to allow him to drop his controversial edict more quickly. Others feared it to be another grab for power. Non-Islamist assembly members quit the process, which served to increase suspicion against the Islamists.
The outcome of the election and the unrest associated with it are important to the stability of volatile North Africa and the Middle East -- where Egypt is a key player -- and the situation is being watched closely around the world.