Safeway is set to offer ad space on the 'Next Customer Please' bars at its checkouts, the first UK supermarket to do so.
In Your Space, the ambient media contractor, is involved in a head-to-head pitch for the work against an unnamed agency.
At least three companies have expressed interest in using the medium, said In Your Space managing director Jonathan Bramley, including Wrigley's and EasyJet.
Kraft Jacobs Suchard had considered using the bars to promote its similarly shaped Toblerone chocolate, but brand manager Christine Iversen decided the medium was too expensive.
Bramley added that he is in talks with other supermarket chains, including Sainsbury's, about selling the space on their behalf.
He claimed that the checkout bars are 'much more potent than normal point-of-purchase opportunities'. 'We hope to achieve nationwide coverage in a variety of supermarkets,' he said.