The spectacle of the iron-fisted leader being swept from office was certain to resonate elsewhere in the Arab world. Smaller protests have erupted in Egypt, Jordan and Algeria in recent weeks as the region's many autocratic governments, often in power without the underpinning of democratic elections, have come under increasing pressure from similarly frustrated youths.
During a trip to the region this week, Secretary of State Hillary Rodham Clinton repeatedly warned governments there that they must expand political and social freedoms or face unrest or worse. Clinton reacted Friday to Ben Ali's departure with a statement condemning government violence against protesters and calling for free elections.
"We look to the Tunisian government to build a stronger foundation for Tunisia's future with economic, social and political reforms," she said.
The United States has long considered Tunisia an important ally, in part because of Ben Ali's close cooperation with U.S. security officials in fighting al-Qaeda and other Islamist extremist groups. U.S. officials and regional experts say the United States has not been a target of the protests, which have focused mainly on economic issues and political freedoms.
A senior administration official who has closely followed events in Tunisia said the State Department has been quietly pressuring Ben Ali's government to undertake reforms.
The prime minister, Mohammed Ghannoushi, 69, in a solemn appearance on national television, vowed to abide by the constitution in laying the groundwork for a vote to choose a new government as soon as possible, in consultation with all political factions and social groups. He was not flanked by military officers and gave no explanation of Ben Ali's removal.
"Since the president is temporarily without the capacity to carry out his duties, it has been decided that the prime minister would exercise his functions," Ghannoushi said from the presidential palace in Carthage, near the capital, Tunis. "I call on Tunisians of all political and regional tendencies to show patriotism and unity."
President Obama condemned the use of violence against the protesters and urged the government to hold elections that "reflect the true will and aspirations" of Tunisians.
"The United States stands with the entire international community in bearing witness to this brave and determined struggle for the universal rights that we must all uphold," Obama said in a statement released by the White House.