Jenson Button wants to stay with BAR because he believes they, and not Williams, offer him the best chance of becoming Britain's next Formula One champion.
The two teams fought a legal battle over Button's contract last year after the driver signed to join Williams while still tied to BAR.
Although BAR won that battle, Williams say they have a contract with Button for 2006.
However the 25-year-old told Britain's Autosport magazine he had "great respect" for Frank Williams but did not want to return to the team that gave him his debut in 2000.
"I hope people will understand that I want to be with the best team possible and that's what BAR is," he said.
"The team is my best chance of becoming Britain's next world champion.
"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."
Frank Williams said at last weekend's German Grand Prix he expected Button to join the team in January and could see no circumstances that might prevent that happening.
Button hoped Williams would be understanding, however.
"I'll certainly be able to look him in the eye when I see him in the paddock," he said. "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."
Since the 2004 contract dispute, Honda have acquired 45 percent of BAR while Williams are expected to look elsewhere for engines after partners BMW bought Swiss-based Sauber.
"Honda buying in was a major part of me wanting to stay," said 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."
