Toro Rosso team principal Franz Tost says that his outfit would take 2015 Ferrari power units next year, though accepts Red Bull's desire for parity with leading squads.
Red Bull has been vocal critics of partners Renault this year amid suggestions that the parties will be heading for a split at the end of 2015.
However, neither Mercedes nor Ferrari has shown willingness to provide Red Bull with a 2016 power unit next year, leaving Red Bull owner Dietrich Mateschitz threatening to withdraw both the senior team and Toro Rosso from the sport.
It is understood that Ferrari would be open to supplying Toro Rosso with one year old power units, a situation which would satisfy Tost, believing it an improvement on the current Renault product.
"Toro Rosso would accept the 2015 engine, as we think it would be a step forward for us," Tost told the Official F1 website.
"But yes, Toro Rosso is in a different situation than Red Bull Racing. Their DNA is to fight for wins and championships and therefore they want the same material Ferrari will run in 2016."
Tost is wary that the delay in an agreement between the parties could have an adverse impact on its 2016 results.
"The new schedule that brings forward the first race to mid-March - and testing to the last week of February and first week of March - could bring us into troubles," he said.
"We need a decision very soon. I don’t want to talk about a deadline, but the earlier we get a decision the bigger the chances of being ready in time for the tests - or at least for the first race in Australia."