The search, which is being co-ordinated by PHD, The Economist's media agency, will result in the weekly business magazine working with a specialist digital agency for the first time. It has previously produced banner ads by reformatting its iconic red-on-white posters, created by Abbott Mead Vickers BBDO.
The change in strategy has been triggered by the magazine's desire to make more of the net's direct-response capabilities. New campaigns to boost magazine subscriptions and to promote brand extensions such as The Economist's surveys and country guides are expected to break this autumn.
The Economist is concentrating on increasing global subscriptions. The magazine already has a circulation of one million copies worldwide, half of which come from readers in the US.
The title's parent company, the Economist Group, has been actively seeking to expand its US presence through acquisition.
In June, it was beaten to the purchase of the US business magazines Inc.
and Fast Company by the Morningstar founder, Joe Mansueto, who paid $35 million (£19.5 million) for the titles. The group has since said it still intends to use some of the £73 million cash it currently holds to diversify in the region.
The Economist was unavailable for comment as Campaign went to press.