With Egyptian President Hosni Mubarak stepping down, many observers wonder if the Muslim Brotherhood, a banned Islamist group, could be poised take on a bigger role in the country.
Even though the Brotherhood has been hammered by state security over the years, it remains a formidable force in Egyptian life.
But just how formidable is an open question. Analysts tend to put its support among the population anywhere between 20 and 40 percent, but no one knows for certain because there have been no free elections and reliable opinion polls.
Some fear the group could threaten U.S. interests on issues including Arab-Israeli peace efforts to counterterrorism if they gain power.
U.S. State Department spokesman P.J. Crowley has acknowledged that the hardline Islamist movement is "a fact of life in Egypt."
In Israel, Binyamin Ben-Eliezer, a friend of Egypt President Hosni Mubarak and until last month a member of Prime Minister Benjamin Netanyahu's Cabinet, warned that elections in Egypt would likely bring the Muslim Brotherhood to power.
"I don't think the Americans understand yet the disaster they have pushed the Middle East into," he told Israel Army Radio.
Egyptian school principal Yusra Mahmoud, a member of the Brotherhood, said she is finally unafraid to publicly declare her affiliation and eager to see the group contest a free election.
"I don't need the Muslim Brotherhood to take leadership of the country, but they deserve a chance to try," she said.
At a Capitol Hill , James Clapper, the U.S. Director of National Intelligence, said the Muslim Brotherhood was "largely secular" in its orientation, but his agency later sought to clarify his remarks.
"To clarify Director Clapper's point, in Egypt the Muslim Brotherhood makes efforts to work through a political system that has been, under Mubarak's rule, one that is largely secular in its orientation. He is well aware that the Muslim Brotherhood is not a secular organization," the agency said in a statement.
NBC's Pete Williams reported that Clapper drew a distinction between Muslim Brotherhood and the Mideast group Hezbollah, saying the Muslim Brotherhood does not have a terroristic side within Egypt.
Here are some facts about the group:
— Schoolteacher Hassan al-Banna founded the Brotherhood in the Suez Canal town of Ismailia in 1928, partly in response to the British occupation of Egypt. It was one of the first and most successful movements advocating Islam as a political program in a modern context.
— Within 20 years the movement had grown to more than 500,000 members, with several branch movements in other Arab countries.
— The Brotherhood once had a secret paramilitary section but it now says it is committed to promoting its policies through nonviolent and democratic means.
— Egypt's government, which has said the Brotherhood is the greatest threat to its survival, has failed to prove any serious act of violence by the movement's leadership for more than 50 years.
— Brotherhood leaders have argued for social and economic reforms; they say that given the freedom to choose, most Egyptians would willingly embrace a form of Islamic law.
— The government has repeatedly denied the Brotherhood the right to form a political party, arguing that the constitution, which the government wrote, bans religious parties. The Brotherhood in turn has said it will not seek recognition as a party under procedures which it rejects as authoritarian.
— The government banned the Brotherhood in 1954 after accusing the group of trying to assassinate President Gamal Abdel Nasser, a charge the Brotherhood has always denied.
— A long period of repression began to ease under President Anwar Sadat in the 1970s. The ban formally remains in place but the Brotherhood operates openly within limits that vary at the whim of the authorities.
— In Egypt, the participation of the Muslim Brotherhood in parliamentary elections in the 1980s was followed by its boycott of the elections of 1990, when it joined most of the country's opposition in protesting electoral strictures.
— In the 2000 elections, Brotherhood supporters running as independent candidates were able to win 17 seats, making it the largest opposition bloc in parliament.
— In the 2005 parliamentary elections, members won one fifth of the seats in parliament, more than any opposition group has held since the overthrow of the monarchy in 1952.
— However, last December the movement said it would shift its political struggle to the streets after November 2010 elections that were "rigged" to ensure it was ejected from parliament.
— In the absence of systematic polling in Egypt, no one has a clear idea how much popularity the Brotherhood enjoys. But the group does have an extensive and well-organized network of committed organizers and has won public support through the charitable work of its professional members. They are also influential in professional organizations such as the doctors' and lawyers' syndicates.
— Government and ruling party officials have been looking for legal ways to reduce the political role of the Brotherhood, official sources say. But in the absence of a workable plan, the government has relied on the police to disrupt the movement's activities. Members can expect to be detained for long periods without trial or charge, especially when elections are imminent.
— The Brotherhood's main foreign ally is the Palestinian Islamist movement Hamas, which has its origins in the group's Palestinian branch. While nonviolent at home, the Brotherhood supports the right to armed resistance to Israeli occupation of Palestinian territory.