CAIRO: For decades Moammar Qaddafi has relied on political and tribal rivalries to rule over Libya, but traditional power structures are crumbling as a popular uprising gains momentum, analysts say.
Qaddafi, who came to power in 1969, quickly established himself as a belligerent and unpredictable leader, erasing longstanding power structures and maintaining personal control through an omnipresent security apparatus.
In 1977, he declared Libya a "jamihiriya," an alternative to capitalism and socialism that, in theory, vested power directly in the people.
But in reality Qaddafi has exercised absolute control, with no political parties and only cosmetic civil society groups, relying on powerful revolutionary committees and members of his Gadafa tribe to crush dissent.
Members of the revolutionary committees, the closest thing to a ruling party, are hand-picked from different Libya tribes based on loyalty with no formal system of membership.
Qaddafi has also played tribes against each other, using a combination of coercion and cooptation to ensure no large alliances tip the balance of power against him.
Tribal affiliation has long played an important role in oil-rich Libya, providing social networks that help advance careers, social mobility and marriage. But their political influence is less clear-cut.
"With urbanisation and development, tribal leaders have less influence on their tribe members," said Mohamed Fadel, an independent Libyan analyst based in London.
"Tribes function in the same ways as large families, and you can have political divisions within that family."
On Monday, the leader's influential son Saif al-Islam warned that Libya could descend into "civil war", implying that clashes that have killed hundreds in the past week were tribal in nature.
But it appears the fighting has been between the regime and its supporters, regardless of what tribe they come from.
In the biggest challenge to Qaddafi's 41-year regime, a broad-based movement calling for freedom and reform is overriding the traditional power structures, analysts say.
"Qaddafi had managed to create a balance between all the tribes and clans, but this system had already started to erode," said Delphine Perrin, an expert on North Africa at the European University Institute in Florence, Italy.
"Today, that power structure is crumbling with some tribes turning against him," Perrin said.
Protests demanding regime change erupted in eastern Libya on February 15 -- four days after the downfall of president Hosni Mubarak in neighbouring Egypt -- and spread within days across the country, leaving hundreds dead and scores wounded, according to human rights groups.
In a defiant, sometimes rambling speech on television on Tuesday, Qaddafi vowed to remain in Libya as head of its revolution, saying he would die as a martyr in the land of his ancestors and fight to the "last drop" of his blood.
Over the years, Qaddafi has worked to strengthen his own tribe -- the Gadafa -- supplying it with arms and money.
"His strong point is the south (Sebha), where his tribe is from and where he brings in mercenaries from Chad," said an analyst in Libya who asked to remain anonymous.
Libya's intelligence chief Abdallah Senussi and Qaddafi's one-time right hand man Abdelsalam Jallud belong to the other two large southern tribes, the Mgerha and the Hsawna.
"To make Qaddafi fall, you must start with this region," the analyst said.
In the last few days, certain tribal chiefs, including those from the powerful Werfalla tribe, have lent their support to the anti-government protests, further weakening the Qaddafi regime.
Away from direct political power, what a tribe can do is provide a security net for dissenting voices, said Molly Tarhuni, a Libyan political researcher in London.
"If one in the tribe stands up, the others feel safer doing so," she said, also pointing to their geographical strength.
"Their ability to mobilise in their location is what makes the Qaddafi regime nervous," she said. "He will try to isolate them geographically from one another."
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