Jenson Button wants to stay at BAR rather than move to Williams because they are the more likely team to win him the world title.
Button has been well ahead of Williams in recent races
The two teams were embroiled in a legal wrangle last season over Button, which saw the Briton stay with BAR.
But on Thursday he told Autosport magazine: "I hope people will understand I want to be with the best team possible and that's BAR.
"The team is my best chance of becoming Britain's next world champion."
Williams say they have a prior contract with the 25-year-old for next season.
Last week team boss Frank Williams said: "We expect him to arrive at Williams at the due period of time."
Button insisted he had "great respect" for the man who brought him to Formula One - Williams signed him for the 2000 season.
But he added: "I'll certainly be able to look him in the eye when I see him in the paddock. We have quite a lot of history together, going back to 2000, so we need to be adult about it and understand the situation.
"I can understand Williams' situation, but Frank has to understand mine as well.
"To be competitive next year any team has to be with a manufacturer that is fully involved.
"The position has changed a lot with Williams from last year. A racing driver's career is short, so you have to make the best of it you can."
This latest row comes a year after Williams and BAR went to court in a dispute over Button's future.
BAR won the battle last year, but Button split with his manager after the row.
And Button added: "Mistakes were made last year but now I am more in control of my future. For me the best thing is to stay with BAR, not just in the short term."
Since then, Honda has bought a 45% stage in BAR while Williams look set to use Cosworth engines next season after partners BMW bought Swiss-based Sauber to set up its own team.
"Honda buying in was a major part of me wanting to stay," added Button. "It shows how serious they are about winning the world championship.
"This is a big decision for me. It's not simply that I am changing my mind from year to year."