By JUDY LINSACRAMENTO, Calif. (AP) â¿¿ Gov. Jerry Brown says he's firmly committed to making national health care reform work in California, but he also is wary of potential costs that could affect state spending for years to come. In releasing his budget for the coming fiscal year last week, Brown pledged to be a reliable partner in implementing the federal Affordable Care Act by expanding Medicaid coverage for low-income Californians. Brown said he wants to move cautiously so the state can run a sustainable program that will not burden taxpayers with new expenses. He set aside $350 million for the Medicaid expansion, but even his top health care aide said the true cost is not yet known. "We're committed to bringing more people to the health care system, but we recognize there are big costs out there, there are big unknowns," Brown said. "We're going to move carefully, but we're going to move with commitment because I do believe people do need decent health care." Starting in 2014, California will help the uninsured gain access to health care in two key ways: through a new insurance marketplace â¿¿ or exchange â¿¿that will offer subsidies and tax credits to individuals and small business; and by expanding Medicaid, the federal-state health program for low-income people. The program is called Medi-Cal in California. While the health insurance exchange is designed to be self-sustaining, Brown said he is concerned about expanding Medi-Cal because the program already consumes 20 percent of the state's $97.6 billion general fund, even as the state splits roughly half the cost with the federal government. It serves about 8 million adults and children, nearly one out of every five residents. Under the expansion, the state would cover an estimated 1.4 million more Californians who make up to 138 percent of the federal poverty line, or about $15,400 a year for an individual, according to a joint report released Monday by the University of California Berkeley Center for Labor Research and Education and the UCLA Center for Health Policy Research.