But Wednesday's demonstration showed the divisions among Egypt's various reform groups - with the Muslim Brotherhood supporters leaving the rally when leftists chanted slogans targeting President Hosni Mubarak by name.
The crowds of protesters massed in and around the Lawyers Syndicate in Cairo, surrounded by thousands of riot police.
Members of the Muslim Brotherhood - all men - made up the bulk of the demonstration, some waving copies of the Quran and chanting: "With our blood and soul, we redeem you Islam."
Several hundred members of other opposition groups were in the crowd, mostly leftists, some chanting "down with Mubarak" and "enough with Mubarak".
Those chants prompted Brotherhood supporters to leave halfway through the two-hour demonstration. "We don't believe in insulting persons or institutions, we only object to policies, so we ordered our supporters to leave," Ali Abdel-Fattah, a senior Brotherhood member, told reporters.
"I'm a bit disappointed," secular activist Aida Seif el-Dawla said of the Brotherhood's leaving. The main theme of the protest was support for judges who have said that a constitutional referendum in May was marred by violations.
"Judges of Egypt, the hopes of the Egyptian people are pinned on you, don't let them down"
Banner in Wednesday's protest
"Judges of Egypt, the hopes of the Egyptian people are pinned on you, don't let them down," read a banner at the entrance of the syndicate.
The referendum approved an amendment allowing multi-candidate presidential elections for the first time.
Mubarak's government have touted the change as a major democratic reform ahead of a September election, but opposition groups have said it is not enough and will not dent Mubarak's 24-year hold on power.
There have been numerous
pro-reform rallies this year
Numerous groups have arisen this year holding an unprecedented string of protests demanding Mubarak quit.
The Brotherhood - which is banned but for years has been Egypt's strongest opposition movement - has joined in the wave of demonstrations, launching the National Alliance for Reform and Change last month in a bid to unite factions.
However, while they have shown a level of cooperation rarely seen in the past, relations between the Brotherhood and other groups have been rocky.
The Brotherhood has taken the brunt of government retaliation with hundreds of supporters arrested after their last large protests, in early May.