Powerful Russian businessman Boris Rotenberg has said that he is pushing hard to secure Sergey Sirotkin's place on the 2018 grid.
The matter of Williams's final driver for next season has become the subject of high speculation, with Russian Sirotkin and Robert Kubica vying for the seat.
Last week it was claimed that the British team were ready to end Kubica's comeback hopes by confirming a deal for Sirotkin, but Williams now say that a decision will not be made until January.
Sirotkin's backers, including the SMP Bank owner and billionaire Rotenberg who is reportedly close to Vladimir Putin, are reportedly promising over €15m (£13.2m) in sponsorship.
Rotenberg told Russian media that he is working hard on the deal.
"I never like to talk in advance," he said.
"It's like football, when you only say you want to win the next game.
"We are all hoping and trying to do everything, but it depends not only on us. The main thing is that [Williams] understand us, but in any case Sergey deserves to go to Formula 1.
"He beat the competition, going faster than Kubica and at the level of [Lance] Stroll. So we now have the opportunity to put him into a car."
The 2018 season begins with the Australian Grand Prix on March 25.
