CAIRO — In one of Cairo’s most crowded quarters, where streets are so filled with trash that bulldozers scoop it up, the Muslim Brotherhood has opened not one but two offices. Its most conservative counterpart has followed suit. An Islamist do-gooder with forearms as broad as the Nile has vowed to win a seat in Parliament.

Egypt’s parliamentary election may be nearly two months away, but the contest has already begun in the neighborhood of Imbaba, where the arc of the Egyptian revolution is on display. The clarity of the revolt has given way to the ambiguity of its aftermath, and Islamic activists here who failed to drive the popular uprising — some, in fact, opposed it — are mobilizing to claim its mantle amid the din of protests, confusion and, last week, violence.

Imbaba may not be Cairo — it is more like a distilled version of the city — but it says a lot about where an anxious country may be headed as it approaches an election that will help decide the future character of an unfinished revolution.

From the caldron of frustration the revolt represented, Islamic activists here have built on their formidable charity across a landscape where liberal and secular forces have made almost no impression. Residents debate programs but often have only the agendas of religious parties to go on. Even the most secular voices — the few there are — wonder if it is not time to give the Islamists a chance.

“They’re the only ones organized, and they’re the only one who deliver to people in need,” Amal Salih, a 24-year-old resident of Imbaba, said with a measure of regret.

In Imbaba, as elsewhere in Cairo, the memories of Tahrir Square represent an ideal that seems to grow more pristine the longer the ruling military council delays the transition to civilian elected government. During the revolution in Imbaba, youths made the point that religion rarely drove their demands, even in a pious locale like this one. As security collapsed, neighborhoods banded together, almost spontaneously, to face any provocation, imagined or otherwise.

Residents said a rich businessman who operated boats on the Nile helped organize popular defense committees. In a neighborhood named for blacksmiths, family elders abstained from their usual evenings over coffee in cafes and set up checkpoints. A spice seller named Sheik Salama and butchers from the Qut family helped organize guards for a stretch of street that hosted a branch of Bank Misr and the Munira police station.

“It was spontaneous,” said Magdy Obeid, a young academic in Imbaba. “We participated as Egyptians. We did not know someone was puritanical, Muslim Brotherhood, or whatever. We were just Egyptian, and there was no distinction between us.”

In February, some of the most puritanical Islamists here handed out fliers urging people to support President Hosni Mubarak; with his fall, they seek to replace him with one of their own. Posters on mosques outline a program no different than any liberal agenda, save for item No. 1 — Islamic law — and a number listed at the bottom reserved for female callers.

“The people here are poor, and they have no idea about democracy or politics,” said Ayman Abdel-Wahab, a Brotherhood member sitting in the group’s office, which opened here in July. “They’ll side with whomever they think can offer them help.”

On the walls of mosques like Furqan and Tawba, posters beckon residents to come and get to know the Brotherhood, still the most potent of Egypt’s Islamist currents. Abdel-Wahab said the group tried to serve as an intermediary between residents and overwhelmed local officials, and that it regularly distributed sugar, oil and rice to hundreds of the most needy.

A banner hangs over one of Imbaba’s main thoroughfares trumpeting a Brotherhood celebration of the neighborhood’s best students. (Each received a watch and certificate.) Youths are offered summer trips to beaches. Other Islamist charities provide monthly payments — $15, sometimes a little more — to widows.

Of course, there is nothing new in Islamist activists taking the lead in offering charity in Cairo, but only now is it so intertwined with the fortunes of coming elections.

“Some people say that the services I provide are equivalent to that of 50 members of Parliament,” declared Yasser Suleiman, known by everyone here as Sheik Yasser.

Under Mubarak’s long rule, the divergent currents of Islamists were often grouped under the rubric of “the religious.” That is no longer the case. The Brotherhood now openly competes with groups that have lately become more assertive: the Salafists, the most puritanical current, along with the once-militant Islamic Group, which renounced violence in the late 1990s.

Not even the Brotherhood claims to know the relative weight of each, though some residents blame the Salafists for a new current of intolerance in Imbaba as well as sectarian clashes that erupted this summer with Christians. Rumors are traded furiously of Salafists administering vigilante justice. In one version, a youth stealing tuk-tuks had either his hand amputated or his ear sliced off.

Ayman Abdel-Aziz, a pharmacist whose office abuts the new headquarters of the Salafist Nour Party, nodded with approval at the story. Though calling himself secular, he had grown weary of the crime wave in Cairo; even his business had been broken into.

“These days, you have to deal with those people and instill fear,” Abdel-Aziz said. “Yes, it’s savage, but it’s the perfect way to deal with all those thugs among us.”

He vowed not to vote for the religious currents, but he understood the logic these days. After decades of repressive rule sometimes conflated in the street with the notion of secular liberalism, he said, people were willing to consider alternatives, however austere.

“The argument goes like this,” he said. “Give them a chance. Let’s try them out.”