Marussia chief executive Andy Webb has admitted the team will be powered either by Ferrari or Mercedes engines in 2014.
Cosworth, whose only customer in F1 this year is the Banbury-based team, is expected to leave the sport before the start of the new turbo V6 era.
So with Renault saying recently it is in talks with Toro Rosso but does not want any more customers, Marussia’s choice appears to be between Ferrari and Mercedes.
"It’s obvious," said Webb, "that with the departure of Cosworth then we can choose between Ferrari and Mercedes.
"We’ll talk with both," he told Russia’s Championat.
"It is clear that the price will be an important factor, because the cost will be significantly higher than the current engines," added Webb.
"And we need to make sure we choose the right partner. I hope to be able to announce our decision in the next four weeks."
It is believed that 2013 Marussia driver Jules Bianchi’s connections with Ferrari make the Italian marque the favourite for the deal.
Webb admitted that the final decision should be made as soon as possible.
"The 2014 car is already in the wind tunnel," he said.
"We have already seen a lot of data on the requirements for the engines in 2014," Webb explained. "We have not chosen a partner yet, but we have a lot of information.
"Of course, a quick decision on the engine would help. Preferably by the end of April."