Precise Public Affairs director Robbie MacDuff and Foresight Consulting MD Mark Adams are both believed to have thrown their hats in to the ring.
PRWeek previously reported that three lobbyists - including MacDuff and Adams - were in the running to replace Gill Morris as chair. This week, sources said the field had narrowed.
Morris could not be reached for comment. Her two year-term as chair comes to an end next month and she will then take the newly created post of deputy chair. APPC members will vote for Morris' successor at the body's AGM, which takes place on 12 May.
The management committee had been due to meet on 7 April to decide whether to officially endorse one or more candidate but it is understood no final decision was made.