The Conservatives have appointed PHD to handle media buying. Goodstuff will handle communications planning, and has a campaign strategy ready in case a snap election is called next week.
Meanwhile, Labour has appointed MindShare as its media agency, following the appointment of Saatchi & Saatchi to the creative account last month.
Goodstuff's strategy for David Cameron's Tories is understood to be weighted heavily towards digital communications, and will rely less on posters and TV political election broadcasts (PEB) than in previous campaigns.
The agency, which is part-owned by Omnicom, has already worked with the Conservatives over the past year to engage younger voters and reawaken interest among disenchanted Tories.
Andrew Stephens, a partner at Goodstuff, said: "Most political campaigns suffer from the 'same old, same old' tag, with standard PEBs, posters and door-knocking. Goodstuff and PHD will challenge this truism by helping the Conservatives in a communications world that has changed significantly since the last election in 2005."
Labour declined to comment on its media strategy or on whether a media appointment had been made.
Separately, the Liberal Democrats are seeking a digital agency in light of the increasing chance of an early election.