(CNN) -- Egyptian President Mohamed Morsy signed a decree putting into effect his country's newly approved constitution, the state-run Egynews reported Wednesday.
His signature came after Egyptian voters approved the Islamist-backed constitution by what an election official said Tuesday was a nearly 2 to 1 ratio.
Read more: Egyptians approve new constitution, unofficial results show
During the two rounds of voting, more than 10 million, or 63.8%, voted in favor, and more than 6 million, or 36.2%, voted against, Judge Samr Abou El Maaty, head of the High Election Commission, told reporters.
The referendum passed with 56.6% of the vote in the first round on December 15, when more liberal provinces voted.
In the second round of voting, on December 22, people cast ballots in 17 provinces largely loyal to Morsy and his ruling party -- which backed the constitution.
There was a 32.9% turnout, El Maaty said. Nearly 303,400 votes were excluded because of voting irregularities.
Egypt opposition's post-referendum plans
An Egyptian man casts his vote during a referendum on the new Egyptian constitution at a polling station on December 15, 2012 in Cairo, Egypt. A man dips his finger on an ink pad to mark his vote in the referendum on December 15, 2012 in Cairo, Egypt.
An Egyptian woman casts her vote during a referendum on the new Egyptian constitution on December 15, 2012 in Cairo, Egypt. Egyptian voters queue at a polling station in central Cairo on December 15, 2012 to vote on a new constitution supported by the ruling Islamists but bitterly contested by a secular-leaning opposition.
An Egyptian electoral official oversees voting activities as people cast their vote at a polling station in President Mohamed Morsi's hometown Zagazig in the Nile Delta on December 15, 2012.
An Egyptian girl waits with relatives queuing to vote at a polling station in central Cairo n December 15, 2012.
Soldiers check the identity of voters as Egyptian women line-up to cast their vote on December 15, 2012 in Cairo, Egypt.
An Egyptian man receives help with dropping his vote in to a ballot box during a referendum on the new Egyptian constitution at a polling station on December 15, 2012 in Cairo, Egypt.
An Egyptian man smokes a waterpipe, known locally as Shisha, as others queue outside a polling station in central Cairo to cast their votes on a new constitution.
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Egyptian opposition allege vicious abuse Controversy among Egypt's society and institutions had accompanied the draft constitution since its inception.
Read more: Egypt's VP resigns amid vote over draft constitution
Critics said it was passed too quickly. Liberals, Christians and other minority opposition groups said they felt excluded from the Constituent Assembly that drafted it and that the wording did not include their voices. They had sought a new assembly.
Opposition members said the charter uses vague language and will not protect the rights Egyptians fought for in last year's revolution, which ousted former President Hosni Mubarak.
Supporters of the constitution herald what they say is its protection of personal rights, especially its provisions on the handling of detainees in the judicial system, which made capricious use of its powers under the former government.
The international rights group Human Rights Watch said the constitution "protects some rights but undermines others." It "fails to end military trials of civilians or to protect freedom of expression and religion."
Read more: Protests turn violent in Egypt ahead of vote on constitution
The rocky road to the referendum began when judges threatened to shut the assembly tasked with drafting the constitution. Morsy issued an edict in late November declaring his decisions immune from judicial review until the holding of the constitutional referendum.
He also sacked the head of the judiciary, many of whose members had remained loyal to Mubarak.
The Islamist president's opposition saw the moves as a grab for dictatorial powers and poured into the streets, converting Tahrir Square in central Cairo back into the center of public discontent it had been during the uprising that brought down Mubarak.
In response, Morsy dropped his decree, but the situation remained tense. Violence raged, producing incidents that have raised the ire of international human rights groups, though these were not systematic, as was the case under the former government.
Read more: Morsy supporters accused of beating, detaining opponents
The outcome of the election is important to the stability of volatile North Africa and the Middle East -- where Egypt is a key player.
The U.S. State Department acknowledged divisions within Egypt and said there was a need for a broader consensus behind its new democratic rules.
"Many Egyptians have voiced deep concerns about the substance of the constitution and the constitutional process," Patrick Ventrell, acting deputy spokesman, said Tuesday in a statement. "President Morsy, as the democratically elected leader of Egypt, has a special responsibility to move forward in a way that recognizes the urgent need to bridge divisions, build trust and broaden support for the political process."
Egypt needs a strong, inclusive government to meet its many challenges, Ventrell added.
Read more: Top Morsy aide: Small, powerful minority behind Egypt's political upheaval