It is believed Smith will stand unopposed. APPC secretary Mary Shearer said: 'I'd be very surprised if Warwick doesn't become the new chairman.'
He will replace Westminster Strategy chairman Michael Burrell, who is resigning from the post after three years.
Smith has described himself as the 'consensus' candidate, adding that the group, which has a low profile in the media, would not alter direction.
The APPC was recently involved in a consultation process by the Scottish Parliament over its plans to regulate lobbying.
The Parliament had wanted to put in place tough new laws forcing commercial lobbyists to disclose a raft of details about clients and fees or face prosecution.
But following pressure from the APPC and other lobbying trade bodies, the Parliament's standards committee is now backing self-regulation.