Incumbent agency Fishburn Hedges has been placed on alert as the retailer reviews its public affairs arrangements after three years.
Sainsbury's has made initial contact with a handful of agencies including Fishburn, but is yet to begin an official pitch process. The new public affairs contract will not be in place until next spring.
It is understood that the pitch will be overseen by Sainsbury's public affairs manager James Clark, who reports to head of corporate responsibility Jat Sahota.
Sainsbury's recently handed consumer briefs to Hill & Knowlton, Camron PR and Cake.