The car breakdown service, which launched its biggest campaign last year in over a decade, has worked with Starcom since 2014.
Acromas Group, the parent company of AA and Saga Group, hired Starcom after PHD resigned the business in December 2013.
It is understood that Starcom will repitch for the business. The AA is expected to hold pitches in October, with Silk Media acting as an intermediary.
According to Nielsen figures, the AA spent £12m on media last year, with £9.5m on the AA brand and £2.5m on AA Insurance. It is expected that the AA will spend a similar amount on media next year.
The AA works with Adam & Eve/DDB after the creative account moved from VCCP in 2014.
A spokesman for the AA said: "We regularly review our supplier arrangements, but we never comment on speculation."