Jenson Button says he would not move to Ferrari or any other team unless he can win the world championship with them.
BAR-Honda hope to persuade the Briton to sign a new deal, but he could leave for Williams next year and was linked with Ferrari over the weekend.
But he said: "If Ferrari are the sixth best team next year I have no reason to move apart from a nice company car. That's not really enough, is it?
"I want to be with the best team, whoever that is."
A clause in Button's contract gives Williams first option on the Englishman in 2006.
However, Williams have been forced to seek a new engine partner after BMW's decision to buy Sauber, meaning Button could opt to stay with BAR.
BAR boss Nick Fry believes his team can offer Button the world title chance he craves.
"We are very hopeful that Jenson is going to stay with us," he said.
"Honda are a company that has won 11 world championships. At the end of the day he knows they are completely determined to win.
"We will give him the best chance to be Formula One world champion - there is no doubt."
Button finished fifth in Sunday's Grand Prix, earning high praise from his boss.
"He has developed Michael Schumacher-like skills to lead this team," said Fry.
"He did fantastically well this weekend, demonstrating that he is a true champion."
He added: "If he was to stay with us for the rest of his career he would be more than welcome, we would love it."