The wide-ranging account is believed to be worth about £250,000 and is currently held by Fleishman-Hillard.
McCain, the market leader in oven chips, is compiling a shortlist and will be holding pitches in early June. An agency is expected to be in place by July to handle consumer, corporate, trade and crisis PR.
Corporate affairs director Bill Bartlett said: 'We're looking for an agency that can offer us an integrated PR approach to our "It's all good" philosophy - that we're good food from a good company made by good people. It's this holistic approach that we're trying to get across.'
McCain is especially keen to promote the nutritional value of its products. In 2008, the company signed a five-year £5m deal to sponsor UK Athletics as part of a drive to shift perceptions about frozen chips.
The next PR drive will tie in with McCain's latest TV advertising campaign, entitled 'Good Unlimited', created by Beattie McGuinness Bungay. It features an enchanted potato factory, aimed at emphasising the 'wholesome' nature of its products.
McCain Foods is the topselling retailer in the frozen potato market, making £270m per year. As well as its flagship oven chips, the Scarborough-based manufacturer also sells potato wedges, frozen vegetables and frozen pizzas. The company has launched a new range of pizzas this month.
The new agency will work alongside retained Westminster-based public affairs shop EUK Consulting, which is working to persuade MPs and opinion-formers that McCain is making nutritional improvements.
Fleishman-Hillard has been invited to repitch.
McCain appointed Fleishman-Hillard in 2005, replacing The Red Consultancy, which handled McCain's PR for almost four years.
