These assessments of Mr Assad's vulnerability came as one estimate suggested that he could run out of money within three or four months.
Mikhail Bogdanov, the Russian deputy foreign minister, said it was necessary to "look facts in the eyes" and acknowledge the possibility of Mr Assad's downfall.
Russia has been the most powerful ally of Syria's regime for more than 40 years, supplying the army with weapons during the crisis and twice vetoing United Nations resolutions that would have increased the pressure on Mr Assad.
Mr Bogdanov, who serves as Russia's envoy to the Middle East, acknowledged that Syria's rebels were on course to overthrow the president as they captured more and more of the country. (© Daily Telegraph, London)