BEIRUT, Lebanon — The defection of Syria’s prime minister, Riyad Farid Hijab, began like so many others: with coded conversations and furtive planning. He began discussing the idea of fleeing, an aide said, as soon as President Bashar al-Assad strong-armed him into taking the job in June. In recent days, he worked to get his extended family out. Then, early Monday, the prime minister slipped out of Damascus under cover of darkness with his wife and four children, scrambling through the desert as a fugitive.
At sunrise, he crossed into Ramtha, Jordan, shocking the Syrian government — which immediately claimed he had been fired — and spurring jubilation within a weary opposition.
“This is a proof that the political basis of the regime is collapsing,” said Samir Nachar, a leader of the Syrian National Council, the main exile opposition group. “This is the momentum we needed to tell the political and military elite that it is time for them to jump off the sinking ship.”
Mr. Hijab’s journey began when he climbed into a simple car with a driver who did not know his identity, according to an account provided by a Free Syrian Army commander, an activist at the Syria-Jordan border, and Mr. Hijab’s spokesman. He traveled down roads lined with rebel lookouts until he reached a contested stretch of border. Finally, he made his dramatic departure from Syria.
The Assad government — nearly a year and a half into the conflict — remains surprisingly strong where it counts. Its powerful military pounded rebels again on Monday in Aleppo, Damascus and other cities, and many analysts question whether the defection of another Sunni leader, no matter his place in the hierarchy, is enough to swing the conflict to a conclusion. The war, after all, has already taken on a blunt rhythm of violence, sectarianism and revenge that does not necessarily respond to the finer pitches of politics and defection.
And yet the scale of the Hijab defection — involving 10 prominent Sunni families who escaped in small groups over the past week — suggests that Mr. Assad is losing the loyalty of Sunni political and security officials crucial to his minority government’s ability to hold power.
His feared internal security apparatus also seems to be cracking. Mr. Hijab, the highest-level official to leave, was closely watched by the Assad government, which nonetheless failed to keep him from communicating with the opposition for months and arranging for dozens of relatives to leave Damascus, where government agents are concentrated.
“This is someone who was very, very close, and they couldn’t keep him,” said Paul Salem, director of the Carnegie Center for the Middle East. He added that while the impact was not cataclysmic, “it’s a sign of advanced decrepitude.”
“It’s a beginning of an endgame sort of thing,” he added.
Mr. Hijab’s departure came less than a month after four members of Mr. Assad’s inner circle were killed in a bomb attack in Damascus that raised serious questions about the cohesiveness of the embattled government. On Monday, rebels struck again close to the leadership’s core, bombing the third floor of the government television and radio headquarters, which have been used to reassure the population that Mr. Assad remains in control.
No one died this time, but the explosion — shown on Syrian television, where officials insisted it was insignificant — again highlighted the rebels’ ability to breach government institutions.
Defections highlight another vulnerability: betrayal within the ranks of supposed loyalists. Over the past few months, there has been a steady flow of high- and midlevel figures announcing that they have turned on the regime. In recent days, in addition to Mr. Hijab, Syria’s most famous astronaut, an air force officer named Ahmed Faris, fled to Turkey, pledging his loyalty to the opposition.
In Washington, the White House spokesman, Jay Carney, said the defections were “a sign that Assad’s grip on power is loosening.”
“That the titular head of the Syrian government has rejected the ongoing slaughter being carried out at Assad’s direction only reinforces that the Assad regime is crumbling from within and that the Syrian people believe that Assad’s days are numbered,” he said.
Rebel leaders and defectors said that the process for leaving varied. In some cases, military officers have taken their allotted leave and have never returned to their units. Other defectors say they have falsified paperwork or used disguises to get through government checkpoints. In June, a Syrian Air Force pilot simply landed his fighter jet at an airport in Jordan.
Most of the defectors have been members of the Sunni majority, breaking away from a government dominated by Mr. Assad’s Alawite minority. Mr. Hijab, who has served in government for most of his life after receiving a Ph.D. in agriculture, is typical. The well-educated head of a Sunni family drawn into government by Mr. Assad’s father in an effort to add legitimacy to his government, he benefited from the government’s patronage before finally rejecting it.
Two of his brothers followed a similar path, with the opposition reporting that they held high positions at the Ministries of Oil and the Environment before they fled the country. And by leaving, said Sami Nader, a Lebanese political analyst, they are stripping Mr. Assad of his “Sunni veneer.” With the defection of such a senior-level Sunni family, Mr. Nader said, it will be harder for Mr. Assad to claim that his is a national government representing all Syrians.
But few analysts, or even opposition leaders, seemed to believe that this latest high-profile defection would be anywhere near enough to end the conflict. The exuberance surrounding the early reports of Mr. Hijab’s defection partly reflected claims that at least two other cabinet-level officials would be joining him.
Mohammad Otari, Mr. Hijab’s spokesman, said that was never true, and that the plan had always been limited to Mr. Hijab and his family. “There were no ministers involved,” he said. “There was no one left behind.”
Rumors about some kind of high-level defection began to spread late last week. An activist in the border region of Dara’a said that government troops had subjected the area to intensified shelling while the army seemed to be on the hunt for someone important.
“We heard they were looking for high-level officials,” he said. “They went in to every home along the border.”
Mr. Otari said the full details of the escape would be provided later, after the Hijab family reached a location outside Jordan. But he said the most difficult challenge involved leaving Damascus and Mr. Hijab’s home in the upscale neighborhood of Mezze. Scores of government agents were watching. Mr. Hijab, Mr. Otari said, had taken the job of prime minister only after Mr. Assad issued a threat: “You take this position or you die.”
Previously, Mr. Hijab had been the governor in the coastal province of Latakia. An activist who said he had dealt frequently with Mr. Hijab said he appeared to have been selected as prime minister because of his close relationship with Mr. Assad’s brother, Maher al-Assad. But during the initial protests last year, the activist said, Mr. Hijab seemed to have some sympathy for the opposition; he had agreed to keep the military and the police away from the first protests.
Later, after arrests were made at subsequent demonstrations, Mr. Hijab helped in the release of 15 people. “He’s a good man,” said the activist, Rami, who declined to provide his full name because he feared reprisals.
Malek al-Kurdi, the deputy commander of the Free Syrian Army, also said the defection was encouraging because “he has a clean record” and “is accepted by the Syrians.”
Some analysts said he could have escaped only through bribery, paying off all the guards responsible for monitoring him. But Mr. Otari would say only that Mr. Hijab took enormous risks to declare his loyalty to the opposition. “It was the most dangerous and difficult defection that took place since the beginning of the revolution,” he said. “This defection breaks the back of the regime.”