Omnicom Group's GMMB was one of two ad agencies responsible for all of the Kerry campaign's advertising. The other agency, Shrum Devine and Donilon, remains on board.
A Kerry campaign spokeswoman said additional creative resources will be added later. GMMB will still handle media buying for the campaign's ads.
There had been some early speculation about the solidness of Riverfront Media -- the name given to the partnership between GMMB and Shrum Devine -- after Sen. Kerry changed campaign managers last year. Jim Margolis, a partner at GMMB, had been hired by Mr. Kerry's former campaign manager, while Bob Shrum is a close friend of Mr. Kerry. Mr. Shrum's partners, Tad Devine and Mike Donilon, are also Kerry campaign strategists.
Today both the campaign and GMMB cited a fee dispute, not any strategy or personality disagreements, as being behind the change.
"Unquestionably, being a part of Senator Kerry's presidential campaign has been one of the most important efforts our firm has ever undertaken," Mr. Margolis said in a statement. "However, due to proposed contract changes with the media firms, we could not come to an understanding that we regarded as workable."
Kerry campaign manager Mary Beth Cahill in a statement praised Mr. Margolis.
"Jim Margolis and his colleagues at the firm have made an extraordinary contribution to John Kerry's success. We're disappointed that they won't continue in that role, but pleased that his firm will continue to provide the best television placement in the business."