The major bone of contention appears to be the disqualification of Salafist candidate Hazem Abu Ismail from running for president. Tens of thousands of his supporters have demonstrated in front of the defense ministry over the past few days.
But tens of thousands more are protesting the continuation of military rule. And that could be more serious than the Islamist uprising.
The military imposed a 11 p.m. to 7 a.m. curfew (2100 GMT to 0500 GMT) in the Abbasiya district around the defense ministry for the second straight day, according to a military source.
The streets were calm on Saturday as cleaners swept up rocks and other projectiles hurled by protestors during the previous night's violence. Troops responded with fired teargas and charged the crowd to drive them from the ministry.
Eleven people were killed in disturbances on Wednesday.
The New York-based Committee to Protect Journalists said at least 18 journalists had been assaulted, injured or arrested while covering the clashes.
"We call on the ruling Supreme Council of the Armed Forces to identify the attackers and bring them to justice immediately, as well as to release journalists in custody," Mohamed Abdel Dayem, CPJ's Middle East and North Africa program coordinator, said in a statement issued late on Friday.
A presidential election, which starts on May 23-24, will choose a replacement for Hosni Mubarak, who was toppled in February last year. Generals have governed since then but their rule has been punctuated by violence and political bickering.
Many protesters who gathered near the ministry were ultra-orthodox Salafi Muslims furious that a sheikh they backed for president was disqualified from the race. Liberals and others were also there, accusing the army of seeking to manipulate or delay the vote.
The military has dismissed those allegations, insisting it will stick to its timetable of handing over power to a new president by July 1, or even earlier in the unlikely event of an outright winner in the first round of voting this month.
"Our mission ends with a successful handover of power, and we will not let anyone change the declared schedule," an army source told the website of the state-owned Al-Ahram daily.
The race appears to be shaping up to be between Amr Moussa, former foreign minister under Mubarak and Arab League chief, and Abdel Moneim Abol Fotouh, a former leader in the Muslim Brotherhood. Fotouh is being backed by hardline Salafists as well as liberal secularists. He is seen as an alternative to the Muslim Brotherhood who many believe have been acquiring too much power of late.
All of these protests are preliminary. The real contest takes place after the constitution is drawn up and a president elected. Then the tug of war between the military and civilian government will begin in earnest.