The Obama administration could demand that Syrian President Bashar al-Assad quit power as early as Thursday, as it looks to ramp up pressure on the regime to end its deadly crackdown on protesters, officials said.
"The United States is looking to explicitly call for Assad to step down. The timing of that is still in question," a US official told AFP on the condition of anonymity.
"It's part of steps to increase the pressure given the ongoing brutality of the Assad regime," he added.
Another US official said the call for Assad's resignation could come as early as Thursday.
US President Barack Obama's administration has steadily ratcheted up the pressure on a regime that seems impervious to US and international calls to stop a crackdown that Washington says has killed more than 2,000 people since mid-March.
But while several US officials including secretary of state Hillary Clinton and US envoy to the United Nations Susan Rice have said Assad has lost legitimacy to rule, the White House has so far resisted issuing a direct call for the Syrian strongman to leave.
This week the administration unveiled new sanctions on the state-owned Commercial Bank of Syria, the country's largest commercial bank.
Explaining the new measures, the US Treasury said it was "taking aim at the financial infrastructure that is helping provide support to Assad and his regime's illicit activities."
Treasury Under Secretary for Terrorism and Financial Intelligence David Cohen charged that the Commercial Bank of Syria was "an agent for designated Syrian and North Korean proliferators."
Steadily escalating US rhetoric against Assad, including a warning that he is now a source of regional instability, has fueled expectations that the Obama administration will soon formally call for him to go.
But the White House on Wednesday stuck with a rhetorical formulation towards Syria adopted last week, saying the country would be a "better place" without Assad.
When they held their first meeting with Clinton on August 2, Syrian dissidents urged Obama to call on Assad to quit power and pressed for UN sanctions over the regime's crackdown on protests.
One of the dissidents said such a high-profile US call for Assad to quit power would bring more protesters into Syria's streets.