The reversal of sequence, which analysts said could help Egypt's leaders tighten control over the parliamentary results, would not violate the transitional plan, Mansour said in remarks quoted by the state's Middle East News Agency.
The interim regime has repeatedly emphasized its commitment to the military's transitional political road map, or "constitutional declaration," as evidence of its support for democracy.
The road map, made public July 3, the day of President Mohamed Morsi's ousting following a popular uprising against him and his Islamist government, called for parliamentary elections to be held first.
But the military-led regime has faced unrelenting opposition from Morsi backers, most notably from the Muslim Brotherhood, a Sunni Islamist religious, political and social movement.
The interim regime last week designated the Brotherhood as a terrorist group, outlawing its activities and membership in the organization.
Analysts cited by the New York Times said switching the election order would let the newly elected president influence the parliamentary makeup, possibly by forming a political party.
One of the people most often cited as a presidential candidate is Egyptian Defense Minister Abdel Fattah al-Sisi, a general who is also commander in chief of Egypt's armed forces and first deputy prime minister.
As head of the armed forces, Sisi played the leading role in ousting Morsi. Sisi, 59, has not said if he will run.
Hamdeen Sabahi, a moderate secular leftist who finished third in the 2012 election that Morsi won, has announced his intentions to run again in 2014.
Both the presidential and parliamentary elections will be held within six months of a revised Constitution's ratification, Mansour said. A referendum on the charter, which has had Islamic articles removed, is to be held Jan. 14-15.
When Morsi was ousted, the Egyptian army suspended the Islamist Constitution that passed with 64 percent support in a popular referendum Dec. 15-22, 2012, that had only a 33 percent turnout.
The military-led interim regime has promised a return to civilian rule after presidential and parliamentary elections are held.
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