Britney Spears has thrown her platinum-selling career comeback into a tailspin by threatening to cancel her $100 million world tour, The Circus Featuring Britney Spears, which will launch in New Orleans this March.

An insider for The National Enquirer reports,

“Britney doesn’t want to do it, and she’s telling her father Jamie that. All the dates are booked-and $100 million would be lost if she bails.

Both her father and ex-husband Kevin Federline are telling her she has to go on for the sake of her kids and their financial future. Jamie needs this tour for Britney to secure her wealth.”

The tabloid claims the pop tart is feeling the pressure of a grueling training schedule necessary for the 33-city North American leg of the tour.

“She is already exhausted getting in shape….Britney feels like she’s being forced to tour.”

According to The Enquirer, Jamie and Kevin both have a lot to lose if Britney runs away from The Circus.

But Britney, 27, hates the tour’s set-up, which includes Kevin – who has custody of their boys – tagging along. That concession was the only way she could have the boys with her, so she reluctantly agreed.

“Kevin is working on a deal for a reality show based on following her ‘Circus’ tour.”

Is it possible to hate Kevin Federline any more?