Dr Helmut Marko says a decision will be made on Red Bull's line-up after the United States Grand Prix.
Max Verstappen's place in the Red Bull is without doubt, but the identity of his team-mate is far from clear.
Pierre Gasly was demoted back to Toro Rosso over the summer break, with Alexander Albon stepping up and securing fifth and sixth-place finishes in Belgium and Italy.
Daniil Kvyat is also a candidate after making an impressive return to Toro Rosso this year, with Red Bull keen to continue their custom of promoting from within their driver programme.
Upcoming races in Singapore, Japan and Mexico should suit the RB15 better than Spa and Monza, potentially giving Albon the chance to seal a big result before Marko's deadline following the Austin event.
"After the USA race we will evaluate who will drive where in 2020," Marko told Speedweek.
Dr Marko praised the early efforts of Albon and brushed off some speculation regarding the reasons behind his arrival.
"He fits in well, made a strong debut in Belgium and has done what we expected him to do. He was fully there from the first lap.
"His signing had nothing to do with the Thai co-owners of Red Bull. They never spoke. That's all up to us."
As for Gasly, a swift return to the senior line-up seems unlikely, but team principal Christian Horner has not ruled out a comeback further down the line.
"He has to show performance," Marko said of the Frenchman. "He needs consistency."