Anchor Brian Williams (search) is expected to leave CNBC next September and join "NBC Nightly News" full time, sources say.

The move will further pave the way for NBC anchor Tom Brokaw (search) to step down from the "Nightly" anchor desk and help to further familiarize viewers with Williams, who is expected to take over the job after the 2004 presidential election.

Williams, 44, has been splitting his time between his evening CNBC telecast "The News with Brian Williams" and "Nightly" for time.

Williams has been the top substitute for Brokaw for several years