The camera crew
Before a camera crew is formed for any production, the DP will probably have had an interview with the director and the producer. Particularly in television, it is quite normal for them to interview perhaps three DPs before making their choice, even if there was a clear favourite right at the beginning. It is a fortunate DP who is well known enough to the director and producer to be asked to shoot their film without having to be interviewed.
Once the DP is confirmed they will start to look for their operator. Most DPs have a preferred operator with a second choice in mind in case the first is already booked on another production. It is quite acceptable for the director to have a significant input into the choice ...