CBS has not made a formal bid for Viacom after social issues raised a potential roadblock, the sources said. Specifically the two sides are trying to decide who the second in command will be at the combined company.
The battle is between Joe Ianniello, the chief operating officer of CBS, and Bob Bakish, the CEO of Viacom, the sources said.
CBS CEO Les Moonves is to remain at the combined company for at least two years, sources confirmed to CNBC on Monday.
Moonves wants to pick his own management team at the combined company and favors Ianniello as his key lieutenant, the sources said. Meanwhile, Viacom and CBS controlling shareholder Shari Redstone is said to favor Bakish in that role, the sources told CNBC.