Thousands of protesters milled about in Tahrir Square long after sunset on Friday, continuing their "million-person" rally to demand a speedier pace of political reform in Egypt in the five months following the country's January revolution.

Many, but not all, of the demonstrators in Tahrir said they were willing to spend the night in Cairo's city center until their demands were met by the country's interim government.

Jihan Kamel, a young secular activist from Cairo, said she was "a bit nervous" to sleep over in Tahrir. Not because her new political movement forgot to bring blankets and rugs to sleep on in their homemade tent. Or because the only food they brought was cold chunks of falafel kept in an old Kentucky Fried Chicken box.

Kamel said she was more apprehensive about where to find a restroom in the middle of Cairo's crowded traffic circle. Still, Kamel said she and others would stay in Tahrir until the government implemented swifter reform.

"Having a better life in Egypt is worth it," she said. "I've been waiting all day, but it will be worth it."

But it wasn't just the hard dirt floor and lack of pillows in Tahrir that kept all protesters from spending the night.

Egypt's Muslim Brotherhood, the nation's most well-organized political movement, confirmed on their official website that the group would not take part in an "open-ended sit-in" in Tahrir.

Egypt's largest Islamist group joined the protest only at the last minute, and it stopped short of calling for the dismissal of Egypt's transitional military rulers on Friday.

Instead, the Muslim Brotherhood announced its desire for greater national unity in the run-up to the parliamentary elections, scheduled for later this fall.

The reluctance of the Islamist movement to openly criticize Egypt's interim government – as well as its decision to leave the square around sunset – provoked scorn from some protesters.

Al-Ahram, a state-funded local newspaper, reports:

Their decision not to participate in the sit-in was not looked at positively by other groups, especially given that a MB speaker also said on that stage that the group fully supports the army and that parliamentary elections should be held first and on schedule in September.

Organizers' original intention for the Friday protest was to demand that Egypt's government allow the nation to write a new constitution before the upcoming parliamentary elections.  Instead, a recent judicial decision and an unusually chaotic week of unrest took center stage.  

Additional time before the vote, said some secular protesters, would give newer political groups more time to organize their political bases.

Some in the country fear that the Muslim Brotherhood's sheer size and organizational infrastructure give the Islamist group a dominant position to sweep elections in September –  and therefore hold the keys to writing the country's constitution later this year.  

"We definitely need more time to prepare for elections," said Kamel. "Some Egyptians don't even know how to vote at a ballot box yet."