Gov. Jerry Brown is targeting a new part of the budget to close a widening deficit by seeking to reduce state worker costs in his revised spending plan, according to sources with knowledge of his plans.

Brown, who has been in discussions with labor unions, is expected to release an updated budget proposal on Monday. The sources were not authorized to speak publicly before the governor's announcement.

The possibility of cuts to state employees is a symptom of lagging tax revenue. California has collected $3.5 billion less taxes than expected in the current fiscal year, according to the controller, and the budget gap will be larger than the $9.2 billion estimated in January.

Brown spared state employees when he released his preliminary budget proposal earlier this year, but sources said he will now ask them to shoulder cuts as the red ink piles up.

It’s unclear how much Brown wants to reduce employee costs and how he’ll achieve the savings. Costs can be reduced through layoffs, cuts to pay and benefits, or furloughs. The Sacramento Bee first reported the possibility on Wednesday afternoon.

H.D. Palmer, a spokesman for Brown’s Department of Finance, wouldn’t talk about potential cuts before Brown releases his new budget proposal.

Many cuts would require reopening union contracts. But contracts with all 12 public employee unions, representing 182,000 workers in total, don’t expire until July 2013.