McLaren racing director Eric Boullier says his team is pushing 'aggressively' on the development of the MP4-29 and aims to be on the pace by the Spanish Grand Prix in May.
McLaren left the season-opening Australian Grand Prix in the lead of the constructors' championship after Kevin Magnussen and Jenson Button finished in second and third place respectively.
But Boullier estimates that rivals Mercedes and Williams have a significant advantage of the rest of the field, one which McLaren intends to close down by the time the sport returns to Europe.
"It’s true that Mercedes and Williams have some pace, maybe between half and three quarters of a second quicker than the rest of the field," Boullier said during a McLaren teleconference on Wednesday.
"But as for McLaren, we focused a lot of our winter on building a solid and reliable car, because we believed - and Australia confirmed our strategy - that reliability was key to taking big points at the beginning of the season.
"It is true now that we are pushing very aggressively on performance development - we need to clearly catch up the gap to Mercedes and also some others."
Boullier believes that McLaren can be on the pace within the next seven weeks.
"Some other teams have not performed well so far, but clearly once they are delivering full power they will be very fast," he added.
"Our target is to catch up by Barcelona, and build up over the first few races in Europe."