LOS ANGELES, Calif. -

California's health-insurance exchange is setting aside nearly $200 million to fight off projected budget shortfalls as it prepares for a challenging financial future.
    
The agency known as Covered California tallied 625,000 health care enrollments through mid-January, the most of any state.
    
But officials say the agency's survival is not assured, in part because of uncertainty around sign-ups that are key to the exchange's success.
    
Executive director Peter Lee tells the state Finance Department in a December letter that Covered California's greatest vulnerabilities include the "long-term sustainability of the organization."
    
Federal grants that have been its sole source of support - more than $1 billion so far - dry up this year.
    
A state audit last summer labeled the agency "high-risk" because of the difficulty projecting future enrollments.