Jason will go to court later this month to ask Judge Reva Goetz to appoint him in the role alongside the 30-year-old singer's father Jamie Spears.
Mr Spears took control over his daughter's affairs in 2008 after her very public meltdown - he will continue to be co-conservator with her lawyer Andrew Wallet for all the "Womanizer" singer's financial and business affairs.
A source told RadarOnline.com: "This is the natural step because Britney's dad, Jamie, hasn't lived with Britney in almost two years. Britney has been living with Jason and her two sons in a rental house for almost a year-and-a-half.
"Britney's medical doctors think it's a good idea to see how Jason will do as her co-conservator as he is planning on marrying Britney. The two will probably get married later this year, and not anytime sooner."
The troubled popstar- who has two sons, Sean Preston, six, and five-year-old Jayden with ex-husband Kevin Federline
- is keen to have her co-conservatorship lifted to allow her to "call her own shots".
An insider explained: "Britney has said that she feels she is ready to resume control of her life. She has expressed this sentiment on multiple occasions, but her doctor believes that Britney isn't ready for the conservatorship to be lifted. She has come a very long way in the last 18 months especially, but her team wants more time.
"Yes, Britney does live on her own with Jason, and her dad hasn't lived under the same roof with her for years, but she just wants to be able to call her own shots.
"Britney doesn't have a problem with the conservatorship staying in place for her business. Remember, she doesn't have any formal custodial rights as far as her children are concerned. Kevin has agreed to essentially joint custody, but in the eyes of the law she has no rights and Kevin can revoke the agreement that is in place at anytime because of the fact that Britney is still under conservatorship."