Multiple sources with direct knowledge tell TMZ -- just one month ago Jamie was deeply concerned about his daughter's mental health. Our sources say Jamie feared the worst if the judge ended the conservatorship. He believed Britney's mental health was deteriorating.

Jamie, we're told, felt Jodi Montgomery -- Britney's personal conservator -- was not protecting his daughter and felt her motivation was saving her own job.

Jamie told people around him, "She's never getting out of the conservatorship," and our sources say he wasn't saying this to be draconian ... he believed it was necessary for her survival.

Now, Jamie says he believes Britney is able to care for herself, make financial decisions and run her life without any guidance. So, he's asking the judge to end the conservatorship. And, here's the key -- he's asking the judge to pull the plug without doing a mental evaluation.

So, why the radical change? As one source told us ... he's calling their bluff. Multiple sources say Jamie believes Britney has not gotten better ... he thinks she's gotten worse. One source put it this way ... "He knows how mentally ill his daughter is, and has genuinely tried to protect her."

Jamie, we're told, has no love lost for Britney's lawyer, Mathew Rosengart. By filing the latest legal docs, in a sense, Jamie thinks he trumped Rosengart, who has not yet filed a motion to end the conservatorship -- something he calls out in his legal docs. This puts Rosengart in an interesting position ... whether to join forces with Jamie at the Sept. 29 hearing and end the conservatorship, or not.

It's almost like saying, "Okay, you think the conservatorship should end. Then bring it on. Let's see what happens."

One source said they don't believe Jamie really wants the conservatorship to end, and certainly not without a medical evaluation. We're told Jamie does not believe the judge would terminate the conservatorship without a mental evaluation, and he has said privately he's sure that evaluation would present an insurmountable case to maintain the conservatorship.

So, he would get what he wants -- maintaining the conservatorship -- while also ending the lingering attacks targeting him. It might also ingratiate himself with his daughter.