Mohammed Morsi, the candidate from the Muslim Brotherhood's Freedom and Justice Party, faced Ahmed Shafiq, a retired air force general and former prime minister, in a runoff election last weekend.
Both men issued claims of victory. A government source told Egyptian news service al-Ahram that Shafiq will be declared the winner Sunday evening. Morsi's camp, meanwhile, issued more than 100 complaints to elections officials this week.
The Muslim Brotherhood, the news service reports, announced Friday it was uniting with revolutionary political groups to present a united front against what it says is an assault on civilian leadership.
The ruling Supreme Council of Armed Forces made a series of legislative decisions this week that diminish the power of civilian leaders while assuming more general authority. SCAF critics have described it as a military coup.
The Muslim Brotherhood was criticized for dominating Egypt's post-revolution political climate. Al-Ahram, however, reports the group would give non-Islamic movements a seat at the political table as well as key roles in the drafting of a new constitution.
Joe Stork, deputy director of Middle East affairs at Human Rights Watch, said SCAF decisions made the political situation more authoritarian than when the former regime was in power.
"The generals' relentless expansion of their authority to detain and try civilians now goes far beyond their powers under Hosni Mubarak," he said in a statement.