WASHINGTON -

From California to Rhode Island, states are confronting new concerns that their costs will rise as a result of the federal health care law.
   
It's because of Medicaid.
   
Before President Barack Obama's law expanded the safety-net program, millions of people who were already entitled to coverage were not enrolled.
   
Those same people are now signing up in unexpectedly high numbers.
   
For states red or blue, the problem is that they must use more of their own money to cover this particular group.
   
In California, Democratic Gov. Jerry Brown's recent budget projected an additional $1.2 billion spending on the state's version of Medicaid, partly due to surging enrollment.
   
The latest predicament is likely to revive debates about how the federal government can saddle states with unanticipated costs.