Late on Thursday evening, the US and France toned down a draft UN resolution demanding Syria withdraw its forces from Lebanon.
The move has been rejected by Beirut and Damascus.
UN sources said amendments were made to the draft late on Thursday evening in the hopes of securing the nine out of 15 votes necessary for passing the resolution.
Under pressure from other Security Council members, the US and France agreed not to mention Syria by name, although it is the only country with foreign forces in Lebanon.
The resolution aims to head off a move in Lebanon’s parliament to amend the constitution and extend the term of Syrian-backed Lebanese President Emile Lahud for three years after his current six-year term expires in November.
The Lebanese parliament votes on Friday.
Syrian forces entered Lebanon in 1976, initially to protect the Christian community in the 1975-1990 civil war. Later, Damascus viewed its presence there as a force for stability as the country recovered from the bloody conflict.
Damascus and Beirut have also sought to counter Israel, whose troops occupied south Lebanon until 2000 and whose airforce continues to violate Lebanese airspace.
The draft UN resolution calls for "strict respect of Lebanon’s sovereignty" and the withdrawal of some 17,000 Syrian troops from Lebanon.
The resolution notifies the council's support for "a free and fair electoral process in Lebanon's upcoming presidential election conducted according to Lebanese constitutional rules devised without foreign interference or influence".
It would also ask UN Secretary-General Kofi Annan to report to the council within 30 days on whether the resolution had been implemented and would declare the council’s readiness “to consider additional measures” to encourage compliance.
Damascus and Beirut signed a friendship pact in 1991 that sought to coordinate foreign and security policy between the two states, formalising the presence of Syrian troops in Lebanon.