Christian Horner is barracking for Lotus to switch to customer Mercedes power for the 2015 season.
There has been a management change right at the top, with Cyril Abiteboul returning to Renault from Caterham to set up a new structure for 2015 and beyond.
He said preparing "a different version" of the Renault V6 for Lotus "tied up too many resources at Renault and distracted from the development".
Lotus' engine change has not yet been confirmed, but it is clearly part of Red Bull's plan.
"I think we have some good things in the pipeline," team boss Horner said in Hungary. "We are working very closely with Renault (after) their recent management change.
"We have a very good working relationship with Renault," he told F1's official website, "and I think Cyril is doing a great job.
"We are getting much more involved -- something similar to working like a proper works team."
For that to happen, Red Bull will be Renault's clear focus in 2015, with only Red Bull-associated teams to get a customer engine -- Toro Rosso, and Caterham, who use a Red Bull-supplied gearbox.
"It would be positive for us and it makes sense to Renault as well."
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