Jenson Button has stepped up his feud with Williams by saying that a contract he signed with the Formula One team for next season will not be binding.
Button has a long relationship with Frank Williams
The 25-year-old Briton failed last year in a bid to move to Williams and has now decided to stay with BAR-Honda.
"I don't think the contract is binding," said Button, who believes he has a better prospects by staying put.
"And certainly I don't think any team would want a driver that would like to be racing for someone else."
Button was prevented from switching to Williams in 2004 after a legal challenge from BAR team boss David Richards.
He went on to sign a pre-contract with Williams for the 2006 season, but has now changed his mind about honouring that.
"I sat down with Frank and had a few chats about it, told him the way that I feel," said the Englishman.
"He probably does understand that I need to do the best thing I possibly can."
Button hopes that an acrimonious fight can be avoided because of his strong relationship with Williams, who handed him a grand prix debut in 2000.
"The situation is different because I have talked it through with Frank whereas I made the mistake of not speaking to Richards last year and that was one of the biggest issues.
"Me and Frank have always had a very good relationship and this is not helping it but I think it shows how serious I am about the situation."
Button is adamant BAR are the best bet to guide him to a long-awaited first Grand Prix win and is anxious to avoid another spell at a rebuilding team.
"I have been in Formula One for six years now and I am ready to win races," he said.
"I am ready to challenge for the World Championship. I can't wait for another three years to build a team up.
"I need to be with a team that's fulfilling in the short term and one that has a works engine manufacturer."
Williams are expected to have a customer supply of Cosworth engines in 2006 if, as anticipated, they terminate their agreement with BMW.