The partnership works closely with the London Thames Gateway Development Corporation, which is responsible for the delivery of the mammoth project.
Rostered agencies will lobby on transport policy, seek to influence the public inquiry into the proposed Thames Gateway Bridge, and communicate the region's need for Crossrail and a tram system.
Other issues include appeasing environmental campaigners, such as the Commission for the Protection of Rural England, that have voiced concerns about the project's impact.
Thames Gateway London Partnership deputy CEO Tony McBrearty said the rosters, each boasting three agencies, will be in place within three months.
The partnership uses Bean & Co PR and Marketing for event management, and Connect Public Affairs. Both have been invited to pitch for a place on the rosters.