The Muslim Brotherhood in Egypt was banned from politics for half a century.
Now, it looks like the most formidable contender in parliamentary elections due in November and plans to run for half of the seats. It aims to win 35% of the total.
But the BBC reports its move from an opposition group to an official political party since the downfall of President Hosni Mubarak on 11 February has not gone entirely smoothly.
The uprising has produced some divisions in its ranks and rivals are appearing on the scene.
There is also persistent scepticism about the organisation's political ambitions from Western powers and some ordinary Egyptians.
''We're preparing for the elections. We're getting ready to choose our candidates and train them," said deputy vice-president Essam el-Erian.
"We are not targeting a majority. We are working in a wide coalition.
''The Egyptian people must see the main streams represented in the parliament: Muslims, Christians, men, women, youths and elders, liberals, leftists, nationalists and Islamists," he said.
Mr Erian also promised good co-operation with all the international community.
"We have learnt from the lessons of Hamas," he said, referring to the victory of the organisation's offshoot in the 2006 Palestinian elections, which alarmed the West and led to funds being cut off.
The Brotherhood's charity and education work have helped it build a national network of grassroots support.
But the group's structure and leadership style is grating on some younger supporters.
Muslim Brotherhood youth movement members have set up their own party, Egyptian Current.
The BBC reports this got them expelled from the Brotherhood, but they are not the only ones to break away.
In May, former Guidance Council member Abdul Moneim Aboul Fotouh, a popular reformist, said he would run for president as an independent.
Other high-ranking members left to set up the Renaissance, Peace and Development and Leadership parties.
However, the BBC reports that other groups - Salafists, the Islamic Group and Sufis - pose a greater threat to the organisation.
A rally organised in Tahrir Square in late July highlighted widespread support for the Salafi movements.
Having previously shunned politics, their leaders recently registered a party called al-Nour (the Light).
Omar Ashour, a lecturer in Arab politics at Exeter University, predicts an internal struggle that will determine whether the Brotherhood draws closer to secular parties or more puritanical Islamist groups.
"We have to see which factions will dominate within the decision-making process," he says.