Edelman won a four-way pitch, which began last month, to handle the brief.
The agency's remit is to help 'neutralise public receptivity to anti-pharma messages' and increase public interest in Pfizer's own solutions to US issues, such as Medicare and civil law reform.
In the pitch brief, Pfizer said: 'The past year has been a difficult one for the pharmaceutical industry. Public opinion is at its lowest point since 1993, and given the amount of legislative and legal activity surrounding healthcare, we expect that we will remain front and centre in the public consciousness.'
Pfizer senior director of corporate comms Nehl Horton stressed the campaign was still in the discussion stage.
He said: 'We've decided to expand our existing relationship with Edelman to talk about some strategies we might adopt to increase awareness and understanding about our company, and public policy issues that are being faced by us and our competitors.'
A budget has not been set, but sources said it could rise to seven figures.
Edelman has already compiled a team, headed by Edelman health president and global director Nancy Turett.
The team also draws on expertise outside the network, including former Bill Clinton press secretary Mike McCurry's Grassroots Enterprise; The Glover Park Group; and Republican ad and political consulting shop National Media.
Glover Park was one of eight firms to receive the request-for-proposals, though it was not among the finalists.
APCO, Burson-Marsteller, Weber Shandwick and Edelman gave final presentations earlier this month.