Red Bull's Formula 1 future could be saved by a deal to run unbranded Renault engines in 2016, Motorsport.com has learned.
With efforts to secure Mercedes or Ferrari engines having failed, and McLaren blocking a Honda deal, Red Bull is running out of options.
The breakdown in relations between Red Bull and Renault is such that insiders suggest it almost impossible for the partnership to continue in its current guise for another season.
However, sources have revealed that Renault chairman Carlos Ghosn is considering a proposal to sell Red Bull unbranded engines next year in a bid to allow the outfit to remain in F1.
A decision to commit to the idea could be made as early as this week.
It is unclear if the power units will be rebadged with a different name as part of the plan, or will run with no name at all.
When asked in Mexico if Renault was now the only option, team boss Christian Horner hinted at an alternative plan, like the unbranded engines, could be available.
“There are not a lot of options, but there may be something else,” he said.
Horner has claimed that Honda is eager to sort out a deal with Red Bull, but that McLaren chairman Ron Dennis has made clear his strong opposition to it.
“Honda are very keen, but unfortunately they have a contractual status that is between them and McLaren,” said Horner.
“It is nothing to do with us. It is for them to decide among themselves what they want to do.”
When asked if he had spoken to McLaren, Horner said: “I haven't spoken to anybody from McLaren other than Ron Dennis, who is the one guy who has the right of say there.
"And his views were quite clear.”
Time running out
With rivals teams already pushing hard with their car designs for next year, Horner said that his team needs to know in the next few weeks what engine it will use if it is going to make next year's first pre-season test.
“At the moment we are right on the limit to be at the first test,” he explained.
“The team in Milton Keynes have demonstrated their ability to work to massively tight deadlines, and I am sure we will be able to meet whatever targets we need to, as long as we come to a decision in the next couple of weeks.”