Gov. Jerry Brown announced on Saturday that the state's deficit has ballooned to $16 billion, a huge increase over his $9.2-billion estimate in January.

The bigger deficit is a significant setback for California, which has struggled to turn the page on a devastating budget crisis. Brown, who announced the deficit on YouTube, is expected to outline his full budget proposal on Monday in Sacramento.

"This means we will have to go much further, and make cuts far greater, than I asked for at the beginning of the year," Brown said in the video.

Lawmakers and others were hoping that a rebounding economy would help the state avoid steep cuts to social services. But revenue in April, the most important month of the year for income taxes, fell far short of expectations, leading to a shortfall of at least $3 billion in the current fiscal year.

The state has also spent $2.1 billion more than expected, according to the controller, further worsening California's financial health.

Advocates involved in budget discussions say they expect deeper cuts to social services than Brown originally proposed in January. Union officials are also in negotiations with administration officials about ways to reduce state payroll costs, an issue that wasn't on the table earlier this year.

Brown has said there will be even deeper cuts, mostly to public education, if voters do not improve tax hikes in November. He is seeking a quarter-cent increase in the state sales tax for four years and a seven-year hike on incomes of $250,000 or more that will range from 1 to 3 percentage points. He says the measure would raise $9 billion in the upcoming budget year.

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-- Chris Megerian in Sacramento

twitter.com/ChrisMegerian

Photo: Gov. Jerry Brown on Thursday with boxes of petitions to place his tax-hike initiative on the ballot in November. Credit: Rich Pedroncelli / Associated Press