There are several possible answers to that question, and many of them are in evidence in today's Green Brief (#25) - perhaps the most dispassionate and reliable regular roundup of news inside Iran. They include the following. Indented passages below are from Green Brief 25 unless otherwise noted.
1. Economic resistance:
Vast weekly protests and the heavy presence of Basiji’s have had a negative impact on Iranian bazaars; they are finding it harder and harder to stay open. As a result, commerce is slowly coming to a standstill. Reports indicate that the opposition is in the midst of planning more strikes and protests.Also of note on this front: the Mousavi campaign's reported cooptation of the Islamic holiday Itikaf, a 3-day period of state-sanctioned reflection and prayer, for which people are encouraged to stay home from work, as cover for a stealth strike. Some suggested that the subsequent official shut-down of government offices, justified by an intense dust storm, may have been a kind of counter-strike.
2. Some wavering in the ranks:
Reports indicate that many Basijis are quitting their jobs and are being replaced by fresh recruits, many of them under 18.A bit of anecdotal evidence that rank-and-file conservatives are divided by the election debacle: yesterday's WSJ portrait of a fanatically devoted young Basij ended with this tale of his recently busted engagement:
3. Protesters' persistence
For Mr. Moradani, the biggest shock during the election turmoil came in his personal life. He had recently gotten engaged to a young woman from a devout, conservative family. A week into the protests, he says, his fiancée called him with an ultimatum. If he didn't leave the Basij and stop supporting Mr. Ahmadinejad, he recalls her saying, she wouldn't marry him.
He told her that was impossible. "I suffered a real emotional blow," he says. "She said to me, 'Go beat other people's children then,' and 'I don't want to have anything to do with you,' and hung up on me."
She returned the ring he gave her, and hasn't returned his phone calls. "The opposition has even fooled my fiancée," he says.
While mass protests of the sort that culminated on June 20 may be effectively quelled for now, the Green Wave is proving persistent, resilient and innovative:
Delayed reports - just emerging - confirm that protests did indeed take place around the country on July 9th. We also have authentication of mass arrests during this time. Reports of black-outs during Ahmadinejad’s speech [allegedly caused by protestors' coordinated plug-ins of as many appliances as possible] are now being confirmed by mainstream media as well (this was confirmed on twitter three days ago). ..4. Continued resistance from high-level clerics and "old Bolsheviks" of 1979:
People in Tehran are continuing to honk their horns at the sight of Basijis - and chanting anti-government slogans while speeding away. Many people drive with their headlights on.
Many of the same scholars and journalists who have recounted the tightening grip of the Ahmadinejad/Revolutionary Guard Khamenei-backed faction have also noted that powerful elements in Iran's clerical and political elite don't like it -- and in particular, don't like Ahmadinejad. Leading dissenters include the "defeated" presidential candidates; former President and current Chairman of the Assembly of Experts and the Expediency Council Akbar Hashemi Rafsanjani; onetime Khomeini heir apparent Ayatollah Montazari; and the Association of Researchers and Teachers of Qum. That resistance is not going away:
In a letter to the Head of the Judiciary, Mahdi Karoubi – one of the candidates during the election and a key force behind the current protests – asked for the immediate release of all political prisoners as well as arrested protesters. In a letter addressed to Ayatollah Shahrodi, Karoubi claimed that, “People believed in the system, however, the system had been hijacked by a few.” He accused Tehran’s authorities of systematically eradicating opposition. He warned the government of “unimaginable consequences” if the current situation persisted.One would imagine that persistence on the part of rank-and-file Greens would be the life-blood sustaining those persisting in the upper-level power struggle. The statements released by powerful groups and individuals questioning the legitimacy of the elections are always made in the name of the people's right to a voice and the legitimacy of their protests.
Ayatollah Montazeri has released a Fatwa that is very supportive of protesters and their cause. In the Fatwa, Montazeri “condemned violence against protesters as un-Islamic.” He’s pleaded with the government to not play with the name of Shi’ism and Islam with their actions. He hinted that Khamenei’s leadership is standing against Islam, human rationale and National interests – and that he was clearly in the wrong. Reports of Ayatollah Ustadi - Qom's temporary Friday Prayer’s Imam - resigning his position and calling a strike could not be confirmed...
The spokesperson for Parliament's Imam’s Way Faction declared that the government’s legitimacy was “questionable” after what transpired post-election. Reports from Tehran indicate that many members within the Faction are thinking of not partaking in the “vote of confidence” that will be held in Parliament soon (the President selects a cabinet, and then a vote of confidence takes place). The spokesperson added that, “When a Cabinet Minister refuses to answer to the public, then it shouldn’t expect to get a vote of confidence”....
A number of prominent citizens in Tabriz have written a letter to Khamenei declaring that, “people were not satisfied with the election and that they will continue to voice their opposition to Ahmadinejad’s government.”
The people's persistence may continue to be fueled, as in 1978-79, by that peculiar Shiite passion for and response to martyrdom, most obvious so far in the iconization of Neda, the young woman shot to death on the street after stepping out of a car into the midst of the protest of June 20. Today, twitterers are reporting a new martyr:
Sohrab, a high school senior, dies in Evin few days AFTER his mom put up bail 4 his release. #iranelectionBack on June 15, BooMan noted, "It's often said that the  revolution advanced in 40-day stages, as forty days is the traditional period of mourning in Iran's culture."
StopAhmadiNew pictures of Sohrab Arabi (killed in Evin prison) http://bit.ly/JiTM7 #iranelection #neda #sohrab
What will happen on July 30, the 40th day following Neda's death?