President Hosni Mubarak's statement last month that Egypt's next election will involve multiple candidates - instead of being simply a referendum on his rule - unleashed a rush of opposition activity here.
Demonstrations by largely secular and left-wing groups have become commonplace, as have press attacks on the president and his family. But Sunday, with the outlawed but politically powerful Muslim Brotherhood set to join the fray, the regime sent a clear signal on the limits of dissent.
Starting at dawn, the government arrested about 70 members of the Brotherhood in Cairo and three other cities. Among those, Brotherhood officials say, was Abdul Meniem Abu al-Futuh, a senior official who tried to lead protesters to parliament. A few hundred made it within half a mile of parliament, while about 2,000 gathered in Ramses Square in central Cairo.
Egypt's approach to the Brotherhood is likely to put the US in a tight spot. The Bush administration has been pushing hard for more democracy in the Middle East. But while the Brotherhood - like most of Egypt's democracy advocates - would seem to be on board with President Bush's reform agenda, it is also deeply hostile to US policies in the region. The Brotherhood and groups like the Kafaya (Enough) movement - a range of secular organizations with limited grass-roots support - react with hostility when asked if they think the opening is a result of US policy.
Instead, they say, the US props up undemocratic regimes, and its use of force in Iraq was both illegal and immoral.
Mr. Mubarak has allowed unlicensed protests in recent months by Kafaya. But an emboldened Brotherhood, which has offices in every province and is the country's largest opposition organization, was too much for the government to take.
"The reason for the escalation by state security is the difference in size and influence between the Muslim Brotherhood and the other oppositiongroups," says Ahmed Ramy, a Brotherhood member.
It appears that the government - caught between US pressure and an increasingly vocal opposition, emboldened by the Iraq war - is trying to relieve political pressure with a small opening while not risking losing control of the situation.
A similar pattern of behavior has been seen with the government's arrest of opposition member of parliament Ayman Nour. The secular Mr. Nour's Al-Ghad party was officially licensed late last year, the first new party permitted in years. Nour then announced that he would run for president in opposition to Mubarak.
On Jan. 29, the government lifted his parliamentary immunity and then arrested him on charges he'd forged signatures on the petition for his party license. It then held him for six weeks. Nour, who says the charges were fabricated, is out on bail, and the government said last week he would be tried in June.
That incident prompted Secretary of State Condoleezza Rice to cancel a February trip to Cairo.
In recent years, the Brotherhood, which hopes eventually to win power through the ballot box and institute Islamic law, has been pragmatic about directly opposing the government. It has held some protests, but only with permission.
Sunday's protest was its first "wildcat" effort in years, and was met with a show of force. The Interior Ministry said it arrested only 45 members of the group for threatening stability and distributing pamphlets opposing Egypt's system of government.
The opposition has been fortified by Mubarak's promise a month ago to amend the constitution to allow a competitive presidential election. Under current rules, only one candidate is nominated by parliament, which Mubarak's National Democratic Party controls.
"We assume that the rules for the election will make it impossible to legally put forth viable opposition candidates,'' says Abdel Halim Qandeel, an editor at the anti-government Al-Arabi newspaper and an organizer behind Kafaya. "But there is an opening here. For the first time, there's open criticism of Mubarak and his family. We need street protests to break the barrier of fear around political activity."
Mr. Qandeel concedes that his movement is "still small," but says Kafaya can take credit for stirring the Brotherhood.
"The Brotherhood is like an enormous body with a very small brain. It takes time to get it moving," he says. Qandeel, a secular socialist whose vision is sharply at odds with the Brotherhood, says he's happy they're becoming more confrontational.
"They don't want to miss out - our pressure forced them to organize their own demonstration," he says. "This isn't necessarily a bad thing. Everyone has to fight Egypt's political stagnation."
In recent weeks, the Brotherhood has been outlining its demands for change. In a new pamphlet, the organization calls for the canceling of all laws limiting freedom of assembly and expression. It particularly wants to abolish Egypt's Emergency Law, which has been used for decades to control the political opposition.
The Brotherhood, which was rooted in Islamic militancy of the mid-20th century, renounced violence in the 1970s. Though officially outlawed, it is partially tolerated. Though it can't run candidates for office, it has about 15 members who ran as independents in the 454-seat parliament, making them the largest opposition group.
Many political scientists say that truly free elections might take the Brotherhood to victory. In the short term, that could complicate US policy in the Middle East.
While the current US position is that democracy will best safeguard US interests, a Brotherhood-led Egypt would probably cool US-Egyptian relations, spur more frequent denunciations of Israel, and suspend Egypt's peace accord with its neighbor.
Reformers in Kafaya are also hostile to the US, and both allege that America has propped up Mubarak and defied democracy here. The US gives about $2 billion a year in civilian and military aid to Egypt, making it the third-largest recipient of US aid after Israel and Iraq.