The Omnicom agency is thought to be in final negotiations with the recently merged group after a shoot-out against Carat. PHD currently handles the AA's £20 million offline planning and buying while Carat oversees Saga's account.
Online planning and buying, including the AA and Saga's search-marketing work, was not part of the pitch and will remain at Carat after it captured the £22 million account from i-level in January.
The appointed agency will create efficiencies in Saga and the AA's media buying. The pitch was shortened to the two incumbents after Zed Media was knocked out early on.
A Saga spokeswoman said no decision had been made on awarding the business.