With the team's current supplier Cosworth unlikely to build a new power unit for next year's radical V6 rules, Marussia's choice appeared to have boiled down to Mercedes or Ferrari.
"We'll talk with both," chief executive Andy Webb said in March.
He said the price of the engine and energy-recovery 'ERS' package, to be significantly higher than the current V8 configuration, "will be an important factor".
Webb indicated Marussia wanted to make its decision "by the end of April".
That deadline has come and gone, but technical chief Pat Symonds has told Britain's Sky Sports that a 2014 engine deal for Marussia is "close".
He confirmed that Mercedes and Ferrari are the two options, given that Renault have "got enough on their plate".
Probably tipping the scales in Ferrari's favour was Marussia's last-minute signing of Jules Bianchi, who is strongly supported by the famous Italian marque.
Asked if the Frenchman's presence has had a positive impact on the Ferrari talks, Symonds admitted: "It absolutely hasn't done us any harm, it's brought us a little bit closer to Ferrari.
"But Ferrari genuinely wants more teams. Because everything is so new, I hesitate to call us guinea pigs or anything like that, but it's better to have a few more samples of your product out there, finding out what goes wrong and what's working.
"I think they wanted another team anyway and the contact through Jules has done nothing but help," added Symonds.