SACRAMENTO (AP) — Gov. Jerry Brown has told California lawmakers that he intends to call a special legislative session on health care reform at the end of the year.

In a letter dated Thursday, the Democratic governor told legislative leaders that many of the provisions of the new federal health care law cannot be implemented without further guidance from federal officials.

Brown does not specify exactly what he wants lawmakers to consider, but his chief health care adviser said California needs time to make statutory changes to meet a Jan 1, 2014, deadline for launching a health care exchange. The exchange will be designed to provide consumers a marketplace to purchase affordable insurance coverage.

Diana Dooley, secretary of the California Health and Human Services Agency, said state officials will use the next few months to figure out what changes need to be made.

The special session is expected to happen in December. It will enable the administration to begin making preparations for the exchange because any bill enacted in special session can take effect in 90 days. If the bills were passed instead during the regular legislative session in 2013, they could not take effect until the following year.

"We know that there are likely to be issues that we're going to need statutory authority for it," Dooley said Friday. "We don't really know what those are at this point, but I thought it would be helpful to let everybody know that we're thinking ahead, that we recognize that we're on a very fast, tight time track to get this ready for January 2014."

Eligibility and enrollment systems, building technology infrastructure needed to run the exchange, working with county service centers, and doing community outreach are among the issues the state needs to begin addressing, she said.

California has been among the most aggressive states in adopting rules to implement President Barack Obama's signature law, which was upheld this year by the Supreme Court.

There are 7 million Californians who lack insurance because they cannot afford existing plans or have been refused coverage by insurance companies. Peter Lee, executive director of the California Health Benefit Exchange, has said more than 3 million uninsured residents will be able to buy affordable coverage as a result of the federal reforms.

The state already has banned insurers from refusing coverage for children with pre-existing illnesses and allows young people to remain on their parents' plans through age 26.

Rhys Williams, spokesman for Senate President Pro Tem Darrell Steinberg, says lawmakers still need to take up three health care-related bills before this year's regular legislative session finishes at the end of the month.