And while Syrian government forces are preparing for the final battle in Damascus, Biden administration officials, watching the rapid advance of the rebels, estimate that the regime of Bashar al-Assad may collapse within the next few days.

Officials who spoke to CNN pointed out that this is not an official estimate as opinions vary, but stressed that the prevailing view is that by next weekend the Assad regime will probably have collapsed.

Under the weight of developments with Syrian rebels moving ever closer to the capital, President Bashar al-Assad is making a last-ditch effort to stay in power.

According to Bloomberg, the Syrian president, through indirect diplomatic approaches to the US and President-elect Donald Trump, is negotiating his political survival.

Assad ordered his army to retreat to defend Damascus, effectively ceding much of the country to the rebels, who seized the major cities of Aleppo and Hama in a swift offensive last week. According to the latest information, they have already entered Homs and surrounded Damascus, occupying suburbs of the capital.

The Syrian president is seeking a deal that would allow him to retain territory his military controls or guarantee his safe passage out of Syria, the sources told Bloomberg.

One proposal Assad has made to the US through the United Arab Emirates is for Syria to end all engagement with Iranian-backed militant groups such as Hezbollah if Western powers exert influence to end the fighting.

At the same time, Assad sent the Syrian Orthodox Patriarch of Antioch and All East Ignatius-Ephraim II to meet Hungarian President Viktor Orbán to convey what he sees as an existential threat to Syria’s Christian minority if the Islamist rebels prevail. His intention is for Orbán to convey the message to the incoming US president, Donald Trump.

It is a dramatic turn of events for a dynasty that ruled Syria with an iron fist for half a century, crushed peaceful protests in 2011 and clung to power through years of civil war that sparked one of the worst humanitarian crises of modern times. Iranian and Russian military support were crucial to the 59-year-old president’s survival, but both are now preoccupied and weakened by other conflicts.

“Assad is in huge danger, it’s almost like in 2015 when the rebels were at the gates of Damascus,” said Sergei Markov, a political adviser to the Kremlin.

The West, including the US, was caught off guard by the rebel advance. Many Western officials estimate that it will be difficult for Assad to remain in power.

The fall of Homs, Syria’s third-largest city, could cut off the highway linking Damascus to the Mediterranean, an area that is a stronghold of Assad and his Alawite followers.

The president’s whereabouts are unclear, although he is believed to be in Damascus or his home town of Al-Qardaha, near the Russian Khmeimim air base. It is also likely to be located in the capital of Iran, Tehran.

Assad’s office issued a statement condemning “rumors and fake news”, saying the president remains in the capital.

Assad ordered most of Syria’s remaining army – estimated at 30,000 to 40,000 fighters – to return to defend Damascus. An army spokesman said in a televised address on Saturday that it was strengthening its defenses around the city, but also in southern Syria.

As rebels have encircled Damascus from the north and south, Iran has withdrawn, keeping its military advisers around the capital. Some Tehran-backed Iraqi militias have also returned to their country after the government ceded the eastern city of Deir Ezzor to US-backed Kurdish fighters, Bloomberg reports.

Russian personnel now remain mostly around the capital and at Khmeimim Air Base and Tartus Naval Base.

After meeting his Iranian and Turkish counterparts in Doha on Saturday, Russian Foreign Minister Sergei Lavrov said Moscow was “trying to do everything to not allow terrorists to prevail”.

Trump, for his part, said on Saturday that pulling out of Syria might be “the best thing that could happen” to Russia, while stressing that the US should not get involved in the conflict.

The communication channels

Russia has launched airstrikes around Homs to try to halt the rebel advance. But with the Kremlin’s help not enough, Assad is pushing behind the scenes for negotiations.

A key goal is to maintain control of a part of the country and opt for Turkey’s proposal for a political transition and the possible return of millions of Syrian refugees, a major issue for Ankara.

Assad is also proposing a new constitution and holding talks with the exiled political opposition, according to Bloomberg’s sources.

It is unclear whether the efforts will bear fruit. Events on the battlefield have their own dynamics, and even countries like Turkey that have influence over the rebels may not be able to fully control events.

“I don’t think any of these outside forces have the power over their proxies to change the course of events,” said Andreas Krieg, director of London-based MENA Analytica Ltd. “Right now most bets are that the Assad regime may not be able to last.”

Visit of the Patriarch

In this context Assad sent Patriarch Ignatius Ephraim II to Hungary on Monday to convey his fears. Syria’s Christian community makes up about 10% of the country’s population of 24 million.

Trump’s entourage had no comment on the matter, but sources said he sent his Middle East adviser, Mashad Boulos, to the United Arab Emirates on Saturday to discuss the situation in the region.

Assad has followed similar tactics in the past. HTS leader Abu Mohammed Al-Jolani and other rebels have sought in recent days to allay fears among Syria’s Christians and other minorities that they will impose an Islamist government.

Assad’s own Alawite community, which has stood by him since 2011 and paid a heavy price to defend the regime, also seems to sense the end may be near.

Nariman, an Alawite woman, said she, her husband who is in the security forces and their 23-year-old son fled to their ancestral village near Jableh in western Syria. She said there were many families like hers.

No one is going to fight for Assad this time, he added.