The roar of chants, songs and noisemakers was deafening for hours outside the offices of Lebanon's prime minister, besieged Friday by hundreds of thousands of supporters of Hezbollah and its allies seeking to oust his U.S.-backed government.
Inside, behind heavy security, embattled Prime Minister Fuad Saniora was holed up, determined to hold out against what he calls a Syria-backed coup.
"Pack your bags, Fuad, and leave us and the country in peace," shouted many in the crowd in a sea of Lebanese flags.
In a carnival atmosphere, the protesters, a majority of them teens and young people, waved their fists, climbed light-poles and cheered nationalist and songs blaring through loudspeakers. At one tense moment, the crowd closed streets leading to the government building, until high-level contacts persuaded them to open one road.
"We don't want America to rule us," said Hashem Aoun, 16-, reflecting his camp's belief that the United States now dominates Lebanon and is steering it in the interests of Israel.
Estimated at between 800,000 and a million, the rally was a show of power by the pro-Syrian Shiite Muslim Hezbollah - far larger than last week's progovernment demonstration after the assassination of Industry Minister Pierre Gemayel.
When most of the crowd dispersed in the evening, thousands remained, setting up a tent camp outside Saniora's offices in what Hezbollah says will be an open-ended protest until he goes.
That likely means a protracted confrontation that could last for days - even weeks - and could tear Lebanon apart between anti-Syrian politicians who control the government and pro-Syrian forces led by Hezbollah.
"Hezbollah and its allies, with support from Syria and the Iranian government, are continuing to work to destabilize Lebanon," said U.S. State Department deputy spokesman Tom Casey.
John Bolton, the U.S. ambassador to the United Nations, called the Hezbollah demonstration "part of the Iran-Syria- inspired coup d'etat."
Hezbollah and its allies demand a third of the seats in Saniora's Cabinet - enough to veto its decisions. They cite Lebanon's constitution, which says the Cabinet should represent all communities in the country.
Saniora has insisted that only Parliament, where his allies hold the majority by five votes, can change his government. Parliament elections are due in 2009.