StrategyPage.com has a nice summary of what's happening in Syria as the repression apparatus of the state is failing to keep a lid on unrest:

Police states are now under more pressure because of the growing popular unrest, and Syria is a test of whether the traditional means of repression will work. In economic terms, only about ten percent of the population benefit from a dictatorship. This fraction of the population supplies the manpower for the secret police (about 50,000 full-timers on the payroll) and the leadership of the armed forces (300,000 troops and 100,000 paramilitary, the majority of them Sunni, led by largely Alawite officers.) The Alawites are five percent of the population. Sunni Arabs are about 75 percent. Other minorities (Shia, Druze, Christian) will, up to a point, side with the Alawites (a common pattern in the Middle East, where non-Sunni minorities have long been persecuted).

As long as the army remains loyal to the government, a dictatorship can survive. Maintaining that loyalty is difficult, since the most of the troops are conscripts, and Sunnis. Most of these troops are young guys who share the same sense of anger and dissatisfaction as the demonstrators (many of whom are veterans, or young guys waiting to be drafted). The government has already had to be careful where it sends army troops, and what it asks them to do. The soldiers have been showing less enthusiasm for killing civilians, and most of the protestor casualties are caused by the secret police and their gangster allies. This use of gangsters as a secret police auxiliary is common in dictatorships, and it even existed in the Soviet Union.

Ultimately, the secret police are responsible for keeping the soldiers loyal. The secret police have informers in the military, and the reports are indicating that troop loyalty is not improving. This is why the government does not go in for large scale massacres (as Bashir Assad's father did). Bashir apparently believes that if he keeps the body count low, and makes enough convincing reform promises, things will quiet down and the popular resistance will cease. But he has to do that before troop loyalty disappears, and each civilian death erodes that loyalty a little more. None of Bashir's reform promises has really caught on with the population. Bashir is hoping the population will quit before his troops do. If the soldiers do turn on the government, or simply refuse to do anything, all that is left to protect the government is the secret police.

The Iranians have been supplying riot control gear as well as sending in the Quds force to train the secret police in the tactics that proved successful - in the short term - against Iranian protestors. It is also believed that the special foreign assassination squad (Ahmadinehad's old unit) attached to Quds is active in Syria, killing leaders of the protests. But as soon as one protest leader is murdered, another rises up to take his place. 

It is also believed that Hezb'allah has sent operatives from Lebanon to assist in the targeted assassinations.  The question is, can all this repressive state controlled  manpower allow Assad to survive this challenge?

The west has abandoned the protestors in Syria to their fate. There is no chance of a Libyan-style operation to protect civilians and unless Assad does something stupid like massacre hundreds of his citizens, it is unlikely that there will be a universal call for him to step aside. Assad is thought to be useful by many diplomats and analysts in the west who see him as the best hope for peace with the Israelis. This kind of delusional thinking doesn't help the Syrian people who continue to pour into the streets despite a clear threat to their lives.