RABAT (Reuters) - The elimination of rivals and accumulation of power that has kept Muammar Gaddafi in charge of Libya for four decades means that if he were to be killed his system of rule would probably collapse.
He has created a political system of overlapping entities and structures that, whatever their formal function, are subservient to the "brother leader" and his close circle.
"The regime has already been shaken by the defection of core members," said Ronald Bruce St John, author of several books on Libya. "It is highly unlikely that it could also survive Gaddafi's demise."
NATO officials overseeing air strikes on Libya say they are not directly targeting Gaddafi, but have repeatedly hit his main compound in Tripoli and, according to Libyan officials, he had a near-miss when one strike hit a house where he was staying.
One of the world's longest-serving leaders who took office at the age of 27 in 1969, Gaddafi has developed a very personalised ruling philosophy that incorporates elements of Arab nationalism and socialism.
In recent years, the Libyan leader has given his sons greater authority but many say, were Gaddafi to die, power would fragment in a country already divided by tribalism and historical division, and rivalry among his sons.
"Once a key node collapses, regime collapse could come relatively fast," said Shashank Joshi, an associate fellow at the Royal United Services Institute in London. "Internally a key defection or a key death leads to others deciding the game is up and defecting or collapsing."
The Libyan government still retains an army far better equipped and trained than the rebels and the Western powers say they will not introduce ground troops.
Thus Gaddafi's administration could fight on after his departure, even in the face of internal divisions and the whole system of rule splintering.
Officials in Tripoli say the entire Libyan people is engaged in the fight with the rebels and NATO, a battle they say will go on whether or not Gaddafi is in the picture.
"The psychological blow to the regime would be huge but his death would not necessarily resolve this conflict and might even make things worse," said Alex Warren, a director of Frontier, a Middle East and North Africa research firm.
"I think the regime will have made contingency plans for Gaddafi's death. One of the sons, probably Saif (al-Islam Gaddafi), might try to rally support and take on the father's mantle, but that would be a very difficult task."
Powerful Arab rulers have enabled their children to take power after their deaths in countries as diverse as Syria and Morocco, but such successions have taken place during peacetime.
Yet Gaddafi's divide-and-rule philosophy, which extends to his own sons, will make any succession messy. Saif al-Islam has clashed repeatedly in the past with his influential brothers Mutassim and Khamis, Libya watchers say.
"No one son enjoys the support of the general public, military, intelligence and security services, and tribal leaders necessary to build the requisite political coalition, especially in a short-term, crisis milieu," said St John, whose books include "Libya: From Colony to Independence".
"If the Gaddafi family and remaining regime members hesitate, that is do not immediately start shooting citizens demonstrating in favour of the rebellion, a widespread popular revolt could quickly develop in areas like Tripoli currently controlled by the Gaddafi regime."
Even if the ruling system were to crumble, many dangers lie ahead. Iraq is an example of the chaos that can follow a dictator's departure.
U.S. President George W. Bush declared an end to major hostilities only weeks after Iraqi dictator Saddam Hussein disappeared in April 2003. The Iraqi dictatorship's government was ousted, but violence continued for years after Saddam's December 2003 capture and eventual execution.
Public sentiment against foreign occupation became a unifying force for many in Iraq.
Because of Libya's oil wealth -- it has the largest proven oil reserves in Africa -- the well-connected have a stake in continuing some version of the current way of ruling and could try to rally under the banner of anti-imperialism.
"There may be pockets of loyalists in some areas who have a stake in the system and who want to flee with various assets, that sort of thing. But I don't think it will be a catastrophe," said Ashour Shamis, a UK-based Libyan opposition activist.
"If Gaddafi goes that will be the end of the regime. There is no chance of the regime coming back, or even a regime similar to his."
In Egypt, the army stepped in when President Hosni Mubarak was forced from power. Gaddafi's sidelining of traditional government power bases make this scenario unlikely.
"The big difference with Egypt is that Libya doesn't have an army that is powerful enough to hold the reins," said Charles Gurdon, managing director of London-based political risk consultancy Menas Associates. "If he goes, the family goes as well."
There are doubts in Western capitals about the ability of the rebels to step in and run the country.
From its base in the eastern city of Benghazi, the rebels' Transitional National Council has been trying to cast itself as a government-in-waiting.
"The opposition has organised a legitimate and credible interim council ... and when Gaddafi inevitably leaves, a new Libya stands ready to move forward," U.S. Secretary of State Hillary Clinton said this week.
But there are divisions and rivalries within the council itself, with in some cases different officials vying with each other for control of important portfolios.
There are question marks too over whether a rebel movement that has its base in the eastern Cyrenaica region can overcome historical suspicions, dating back to when Libya was divided into three entities, and win over people in Libya's west.
(Additional reporting by David Brunnstrom in Brussels; William Maclean and Emma Farge in London)