Rats are leaving the sinking ship that is the regime of Bashar Assad.

Reuters is reporting that Syrian Prime Minister Riyad Hijab has defected with his family and is in Jordan, ready to join the opposition.

Syrian state media is reporting that he was fired. But a source in Jordan says he defected before he was let go by President Assad.

"I announce today my defection from the killing and terrorist regime and I announce that I have joined the ranks of the freedom and dignity revolution," Hijab said in a statement read in his name by the spokesman, which was broadcast on Al Jazeera television. "I announce that I am from today a soldier in this blessed revolution."

Syrian state television reported Hijab's dismissal as government forces appeared to prepare a ground assault to clear battered rebels from Aleppo, the country's biggest city.

The opposition Syrian National Council said a further two ministers and three army generals had defected with Hijab. That assertion could not immediately be verified.

Hijab was a top official of the ruling Baath party but, like all other senior defectors so far from the government and armed forces, he was also a Sunni Muslim rather than a member of Assad's Alawite sect, which has long dominated the Syrian state.

"Hijab is in Jordan with his family," said the Jordanian official source, who did not want to be further identified. The source said Hijab had defected to Jordan before his sacking.

Assad appointed Hijab, formerly agriculture minister, as prime minister only in June following a parliamentary election which authorities said was a step towards political reform but which opponents dismissed as a sham.

Hijab's home province of Deir al-Zor has been under heavy Syrian army shelling for several weeks as Assad's forces try to dislodge rebels from large areas of countryside there.

Syrian television said Omar Ghalawanji, who was previously a deputy prime minister, had been appointed to lead a temporary, caretaker government on Monday.

Hijab's defection does not materially affect the Assad regime. For months, the weak links in his regime have been sloughed off -- defections or deaths -- leaving only a hardcore of ministers, soldiers, Baath party members, and Alawites to carry on the battle. While weakened considerably, this hardcore will almost certainly stay with Assad through whatever trials there will be in the future.

They don't have any choice. For many of the Alawites, they fear a Sunni takeover would result in their death. For the inner circle, there is the prospect of war crimes tribunals if they lose. For most of the soldiers, death at the hands of the Shabbiha militias awaits any attempt at defection.

The civil war will not end until this hardcore is destroyed. And that could take years.