Iran's supreme leader sought Friday to end the deepening crisis over disputed elections with one decisive speech, declaring the vote will almost certainly stand and sternly warning opposition leaders to end street protests or be held responsible for any "bloodshed and chaos" to come.
But a first sign of possible resistance came shortly after nightfall in Tehran. Cries of "Death to the dictator!" and "Allahu akbar", "God is great" rang from rooftops in what's become a nightly ritual of opposition unity.
The sharp line drawn by Iran's most powerful figure, Ayatollah Ali Khamenei, is a gambit that pushes Iran's opposition to a pivotal moment: either back down or risk a crushing response from police and the forces at Khamenei's disposal, the powerful Revolutionary Guard and their volunteer citizen militia, the Basij.
It also presents important tests for opposition leader Mir Hossein Mousavi.
He now must examine his willingness to challenge the Islamic leadership he once served as prime minister. There are further questions about his ability to control his own followers, who are waiting for a clear response to Khamenei's edict before a rally planned for Saturday.
Since the June 12 election, Mousavi has become the figurehead for a broad collection of demonstrators from the most liberal-leaning reformists to religious conservatives brought together by claims that fraud was behind the landslide re-election of President Mahmoud Ahmadinejad.
Some could be prepared to take their protests to the limit. Many others, however, have no interest in an all-out mutiny against the country's Islamic system and know authorities have the tools to strike back without mercy.
Khamenei was blunt about what a wider fight would bring _ warning those who "want to ignore the law or break the law" will face the consequences.
"They will be held accountable for all the violence, bloodshed and rioting," he told tens of thousands of people gathered for Friday prayers at Tehran University for a speech that was broadcast around Iran and the world.
Police clashed with protesters in running battles around Tehran immediately after the election and the Basij militia had a reported role in attacks at the university. Gunfire from a Basij compound in Tehran also left at least seven people dead Monday.
Khamenei even offered muted criticism of security forces, saying he objected to "misconducts" such as attacks on students. But the full force of the police and Revolutionary Guard has remained in check. And this was Khamenei's implicit message since the Guard and the vast volunteer militia force it controls is under direct command of the ruling clerics.
As he concluded his sermon, Khamenei invoked the names of Shiite saints and began weeping.
Among the worshippers sitting on the carpeted floor of the mammoth prayer hall was Ahmadinejad in a tan jacket and one of his three election rivals, former Revolutionary Guard commander Mohsen Rezaei. Crowds spilled into the campus.
Mousavi and candidate Mahdi Karroubi, the only cleric in the race, were not shown on state TV coverage and apparently did not attend.
Iranian authorities have placed strict limits on the ability of foreign media to cover recent events, banning reporting from the street and allowing only phone interviews and information from officials sources such as state TV.
"The Islamic state would not cheat and would not betray the vote of the people," said Khamenei, standing on a raised platform decorated with Quranic verses and flanked by flowers. He went on to effectively declare Ahmadinejad the winner, calling the election an "absolute victory."
He left open a remote chance that the overall outcome could come under question by the Guardian Council, an unelected body of 12 clerics and Islamic law experts close to the supreme leader. The council investigates voter fraud claims.
British Prime Minister Gordon Brown and other European Union leaders expressed dismay over the threat of a crackdown.
The British Foreign Office told Iran's charge d'affairs in London that Khamenei's comments were "unacceptable and had no basis in fact," a spokesman said on condition of anonymity in line with policy.
Both houses of the US Congress approved a resolution condemning "the ongoing violence" by the Iranian government and its suppression of the Internet and cell phones. It also expressed support for Iranian citizens who embrace freedom.
The Republican-backed resolution was a veiled criticism of President Barack Obama, who has been reluctant to speak too strongly about the disputed election. White House press secretary Robert Gibbs said the resolution is consistent with Obama's message condemning the violence in Iran.