When Obama brought it up with Russian Prime Minister Dmitri Medvedev at the G-8 summit at Camp David last weekend, Medvedev appeared receptive, US officials said, signaling that Russia would prefer that option to other transitions in the Arab upheaval.
"Medvedev raised the example of Mubarak in a cage," the Washington Post quoted a senior official as saying, referring to longtime Egyptian ruler's confinement at his trial.
The unnamed official said Obama had then "countered with Yemen, and the indication was, yes, this was something we could talk about," the paper said.
Obama, US officials said, will press the proposal with Russian President Vladimir Putin next month at their first meeting since Putin returned to his old post on May 7.
Thomas Donilon, Obama's national security adviser, raised the plan with Putin in Moscow three weeks ago, the paper said.
The US plan calls for a negotiated political settlement that would satisfy Syrian opposition groups but that could leave Assad's regime intact under a different leadership.
Its goal is the kind of transition under way in Yemen, where after months of violent unrest, President Ali Abdullah Saleh handed over power to his vice president Abdu Rabbu Mansour Hadi, in a deal arranged by Yemen's Arab neighbours.
The success of the plan hinges on Russia, one of Assad's staunchest allies, which has strongly opposed his removal.
In the past year, Russia has blocked any tough United Nations Security Council action against Assad, arguing that it could lead to his forced ouster and the kind of fates suffered by Col. Muammar Gaddafi of Libya, who was killed, or Hosni Mubarak of Egypt, who was imprisoned and put on trial.
But Russia is facing intense international pressure to use its influence to bring about the removal of Assad as the killings in Syria continue unabated, including the massacre of more than 90 people in a village near Homs that was reported by United Nations officials yesterday.
The Yemen example has been widely discussed in Moscow, so much so that the option has become known by its Russian term, "the Yemenskii Variant," even in the United States.
In part, that reflects Russia's desperation for a solution to the crisis in Syria, where, the United Nations says, thousands of civilians have been killed since protests began there in March of last year.
American officials say they are ready to reassure their Russian counterparts that Moscow would be able to maintain its close ties in a post-Assad Syria.
"Look, we recognise that Russia wants to have a continued influence in Syria," one official said, speaking on condition of anonymity. "Our interest is in stabilising the situation, not eliminating Russian influence," the report said.