Red Bull team principal Christian Horner believes various F1 drivers and teams are waiting on Lewis Hamilton to decide on his future before finalising their own plans for 2019.
Reigning world champion Hamilton is reportedly close to signing a new contract with Mercedes.
Horner remains in talks with Daniel Ricciardo over his Red Bull future and has the option of recalling Carlos Sainz Jr from Renault if the Australian chooses to depart.
Ahead of this weekend's Austrian Grand Prix, Horner discussed the likely contractual developments as he sat alongside Mercedes chief Toto Wolff.
"All of these things are interlinked in some way, shape or form. I think the whole driver market is waiting for Toto's driver to kick that off," said the Red Bull boss.
"As soon as Toto signs his contract, or two contracts, that then will cascade, and Carlos Sainz will be a mechanism within that. It's all down to Toto, really.
"Things are progressing well with Daniel. I think things will be concluded prior to the summer break. Our priority has been firstly to get the engine situation sorted, and now things are progressing well with Daniel.
"I'm sure, in the next couple of weeks hopefully, we'll be entering the finishing straight to get things concluded."
