The announcement comes as part of a reshuffle following Rajoy's appointment as the PP party's presidential candidate. Javier Arena, a strong favourite for the spokesman post, has instead been elevated to second minister for the economy, succeeding Rodrigo Rato, who will become the nation's vice president.
Zaplana's biggest challenge is likely to be the centre-right PP's fight against socialist opposition party PSOE in reigning over next year's general election. Unlike Rajoy, he will not have to deal with incendiary issues such as Spain's strong support for the Iraq war or the widely-criticised mishandling of the prestige oil tanker disaster.
Apart from communicating the PP's political goals, Zaplana, who will remain as labour minister, will try to ensure that Rajoy is not overshadowed by Aznar in the run-up to the election.
Hill and Knowlton's Madrid director Miguel Aballe called Zaplana an 'agile communicator,' adding 'I've heard how he turns questions around. You ask him how unemployment has increased and he's very convincing at telling you it's actually gone down.'