Red Bull will not rule out Renault partnership in 2016
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Red Bull have not ruled out continuing with Renault as their engine supplier next season despite the breakdown of their relationship.
Red Bull are without an engine partner for 2016 after all-but finalising a split from Renault but failing to secure an alternative supply.
Team principal Christian Horner said: "At this point, everything is open.
"Is it likely we'll be with Renault? Difficult to see that would be the case but in F1 nothing is impossible."
Horner said the termination of Red Bull's contract with Renault, which was due to last until the end of 2016, had not been finalised.
However, a continuation of the relationship would be a major climbdown for Red Bull, who have been heavily critical of the French company over the past two years as it failed to produce a competitive engine under F1's new turbo hybrid rules.
Horner, whose team won four consecutive world title doubles with Renault engines, said: "Maybe we have been guilty of being too honest on occasion."
He added: "We have enjoyed a long relationship with Renault - nine years. We have had some good years and some tough years. The last couple of years have been tough.
"We have pushed Renault because we're hungry for success and sometimes it's got uncomfortable.
"We just have to be open-minded and come up with the best solution for the team."
Renault Sport boss Cyril Abiteboul told Autosport: "Frankly, when you see the way we have been treated, it's going to be a very difficult sell to my board and to my executive management to do something else to what is currently planned."
Red Bull have been in talks with Ferrari since Mercedes told them in September they were not prepared to give them an engine.
But Ferrari have so far offered Red Bull only a supply of their 2015 engine, not their definitive 2016 design, which will be supplied to customers Sauber and Haas - the new US-based team - as well as to their factory team.
Ferrari's position is Red Bull approached them too late and they are not set up to supply any further 2016 engines.
Mercedes F1 team boss Toto Wolff reaffirmed at this weekend's Russian Grand Prix that the German company would not supply engines to Red Bull.
Red Bull owner Dietrich Mateschitz has said he will pull both his teams out of F1 if he cannot get an engine that allows them to be sufficiently competitive.
The team have previously said they think it will be another two years at least before Renault is able to produce a competitive engine.
The 2015 Ferrari engine is very similar in performance to the standard-setting Mercedes and in the region of 50bhp more powerful than the Renault.
Horner said: "I am working very hard to try to find a solution in the coming weeks. We have to find a way to get as competitive an engine as possible in the car and to satisfy our shareholders and Mr Mateschitz."