Williams have made clear that their door may be open to not only Jenson Button but also Sergio Perez for the 2017 season.
It is an uncomfortable period for the Grove team's existing drivers Felipe Massa and Valtteri Bottas, with plenty of rivals including Daniil Kvyat and Lance Stroll having already been linked with their seats.
Now, deputy boss Claire Williams has told PA that current McLaren driver and Formula 1 veteran Button is a key target - but not the only option.
"I am not sat here waiting for Ron Dennis to make his decision or for Jenson to make his decision," she warned.
Also open at present is the future of Perez, after the Mexican rejected Force India supremo Vijay Mallya's recent claim that he is definitely staying for 2017.
The 26-year-old Mexican said at Hockenheim that his future can only actually be decided by himself and his multiple sponsors headed by billionaire Carlos Slim.
"Sergio has done a great job this year, he is an intelligent driver, and of course he is going to be someone we are looking at," Williams said.
"He is [also] very eloquent, so commercially he would be strong for any team. Of course he is going to be someone you'd consider if he is available."
The 2016 championship resumes after the midseason break on August 28 in Belgium.
