Williams have told Jenson Button they will not "wait around" for him or McLaren to make a decision on 2017 before deciding its own line up for next year.
Button, whose McLaren contract expires at the end of this year, has been linked with a return to Williams, where his F1 career started in 2000. McLaren is delaying a decision between Button and the highly-rated Stoffel Vandoorne, who scored a point on his debut in Bahrain while deputising for the injured Fernando Alonso, until after the summer break.
Williams deputy team boss Claire Williams has admitted Button is very much on the team's wish list for next year but is refusing to let his situation at McLaren dictate Williams' own future.
"We will own our driver line-up decision, and I am not sat here waiting for [McLaren chairman] Ron Dennis to make his decision or for Jenson to make his decision," Williams told PA Sport. "It it is not about what other people are doing. I am not going to be waiting around because that is just not the right mentality for a team like ours to have.
"It would be a great story, but he has to make the right choice for him, and we have to make the right choice for the team."
Williams thinks Button's talent behind the wheel and appeal away from Formula One would make him an ideal driver for the team.
"He started his career here, but more importantly Jenson is a great driver, and he has still got a lot of fight left in him. He is a great talent in the car, but also outside of the car and we need a driver like him. That is not to say our focus is purely on Jenson.
"When I talk about the criteria that we are looking at, it is the talent in the cockpit, the intelligence to feed back to the engineers, and for us, as an independent team, the commercial factors are going to play a part in the decision-making process too. You can't have an unknown driver in your car. It is just not going to work."
Williams also spoke about Sergio Perez, who has refused to commit to Force India despite Vijay Mallya's insistence he has been retained for 2017. In Germany the Mexican admitted he could leave Force India at the end of the season as he and his sponsors continue weighing up his options.
"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. I have only met him briefly on the odd occasion.
"He is very charming. He is 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."