Egypt's opposition groups say government proposals on how to end the political crisis are not enough.
The banned Muslim Brotherhood and other groups took part in landmark talks with the government following days of protests aimed at forcing President Hosni Mubarak to resign.
The government has proposed a reform of the constitution, but the opposition said the talks were only a first step.
US President Barack Obama said Egypt would not "go back to what it was".
Speaking to Fox News on Sunday, he said: "The Egyptian people want freedom, they want free and fair elections, they want a representative government, and so what we've said is, you have to start a transition now."
He added that the US could not dictate to Mr Mubarak what he should do, but that it could advise him "the time is now for you to start making a change in that country".
President Mubarak has refused to resign, saying that to do so would cause chaos. He has instead said he will not stand for re-election in September.
In all, six groups were represented at Sunday's talks hosted by Vice-President Omar Suleiman, including a coalition of youth organisations, and a group of "wise men".
Egyptian state TV said the participants had agreed to form a joint committee of judicial and political figures tasked with suggesting constitutional amendments.
It was the first time the government and the long-banned Brotherhood have held talks.
However, the Muslim Brotherhood said it would only take part in the talks if the government made progress on meeting its demands:
- the immediate resignation of President Mubarak
- lifting emergency laws
- dissolving parliament
- releasing all political prisoners
"Our demands are still the same," senior Brotherhood figure Essam el-Erian told reporters in Cairo. "They didn't respond to most of our demands. They only responded to some of our demands, but in a superficial way."
The BBC's Jon Leyne in Cairo says opposition members and the "wise men" who were also there told him they were sceptical of the government's moves.
Leading opposition figure Mohamed ElBaradei was not at the talks but one of his representatives met Vice-President Suleiman separately.
Speaking to the US network NBC, he described the process as "opaque".
He said he was proposing a one-year transitional period where Egypt would be run by a three-member presidential council as it prepared for free and fair elections.
The Brotherhood had previously said it would not take part in the negotiations.
The Islamist group is Egypt's most influential and well-organised opposition but it remains officially banned and its members and leaders have been subject to frequent repression.
The Muslim Brotherhood denies accusations that it is seeking to create an Islamist state in Egypt.
Tens of thousands have again joined demonstrations in Cairo and other cities, calling for him to quit.
Meanwhile, many banks opened for the first time in a week, drawing long queues as people waited to withdraw money.
The government is seeking to revive an economy said to be losing at least $310m (£192m) a day.
Many shops, factories and the stock exchange have been closed for days, and basic goods have been running short.
Correspondents say many Egyptians have been wondering how quickly daily life will return to normal regardless of the outcome of the struggle for power.
But they also say there is no let-up in the magnitude of the protests in Tahrir Square, and the mood is almost back to the festival atmosphere of the first few days, with many families and young children in attendance.