Lawmakers tied to Shiite resistance movement Hezbollah led opposition leaders in mass resignations that brought down the Western-backed government of Saad Hariri in January.
Hezbollah was upset with Hariri's continued support for the Special Tribunal for Lebanon, which is finishing its investigation into the assassination of former Lebanese Prime Minister Rafik Hariri -- Saad Hariri's father -- in 2005.
U.S. Ambassador to Lebanon Maura Connelly said any new government that emerges from Beirut must respect the work of the tribunal.
"Any government that claims to be truly representative of all of Lebanon would find it impossible to abandon the tribunal's efforts to end the era of impunity for assassinations in the country," she was quoted by Lebanon's Daily Star newspaper as saying.
Lebanese Prime Minister-designate Najib Mikati is moving closer to forming a Cabinet that will likely be dominated by Hezbollah and its allies in the March 8 coalition.
"The birth of the new government is (coming) in a matter of days, either at the weekend or early next week," a source told the newspaper on condition of anonymity.