Heinz has agreed to buy Danone's HP Foods business, which includes the HP, Daddies, Amoy and Lea & Perrins brands, for $855m (£470m).
The pitch for the £6m account, which is being handled by Agency Assessments, follows HP's decision in April to part with incumbent ad agency Mustoes over differences in creative direction.
Industry insiders have suggested that Heinz's roster agencies, which include Leo Burnett, EHS Brann and WCRS, may be invited to join the pitch.
HP Foods was unavailable for comment.
The company spent £3.1m on advertising across its brands last year. Heinz is expected to maintain marketing investment in HP.