SACRAMENTO — The California Senate on Thursday approved the largest expansion of Indian gambling in the state since tribes were given the authority to operate casinos.

The agreements now go to the Assembly. If passed by that house, they would allow tribes to operate an additional 22,500 new slot machines, the equivalent of more than 10 Las Vegas-sized casinos. It would represent a 50 percent increase in the number of slots currently operating in the state’s Indian casinos.

Gov. Arnold Schwarzenegger, who negotiated the agreements with the tribes last year, is counting on the Legislature to approve the compacts by mid-May to help balance his spending plan for the budget year that begins in July.

He is relying on tribes installing thousands of the slot machines within months and beginning to pay the state $500 million annually in casino winnings to close the state’s chronic budget deficit. The state’s nonpartisan budget analyst has said such expectations are unrealistic and that the state may not see significant revenue from the compacts for years.