Robert Kubica has repeated his claim that he will not wait too long for Williams to make its decision about 2019.
Claire Williams has admitted the British team is considering the Pole as well as Esteban Ocon or Sergey Sirotkin as candidates to be George Russell's teammate next year.
"We're taking our time with it. We're not in any mad rush," she insisted in Austin.
Reserve driver Kubica is believed to have put together a handsome sponsorship purse to offer Williams for 2019, but the driver says he is not going to wait forever.
"Time does not stand still," he said. "I do not want to wait as long as I did last year.
"I cannot wait until December," Kubica is quoted by Speed Week.
"I think the team is going through different scenarios and testing them, and that's a good thing. And I'll take care of a few other things on my part," he added.
"I'm certainly looking at other options too, because I do not want to end up finding out that it's too late for anything in 2019.
"The goal is to race in formula one, and if that's not possible I may still be in the paddock or I may go into another championship.
"What is certain is that will be decided in the next few weeks, at least as far as my side is concerned," said Kubica.