The state Senate voted to expand legalized gambling in the state on Thursday by approving a bill that would install thousands of slot machines at the state's horse and dog tracks.

State senators voted 26-9 in favor of the legislation, which would install 2,000 slot machines at all four Massachusetts racetracks. Two of the tracks are in the district of Senate President Robert Travaglini, D-Boston.

Sen. Michael D. Morrissey, D-Quincy, said Massachusetts residents spend hundreds of millions of dollars a year at out-of-state casinos, such as Mohegan Sun, and that the state could use the money the slots generate, including paying for help for compulsive gamblers.

"I like to think that there is a clear majority of people who'd be supportive of the idea," Morrissey said. "It does save the existing industry. It does provide hundreds of millions of dollars for the Commonwealth."

Thursday's vote was the first time the Senate has voted on a bill to add slot machines to dog and horse tracks, according to Travaglini. Sen. Susan Tucker, D-Andover, said gambling is not a financial solution for the state.

"The piece of the slot pie you've been promised will be eaten before you finish your dinner," she said.

Rep. Daniel Bosley, D-North Adams, chairman of the House Economic Development Committee, said this week he didn't think the bill would pass in the House. Even if it did, it's not certain it could sustain a veto from Gov. Mitt Romney, who opposes bringing slot machines or casinos to Massachusetts.

Under the bill, Suffolk Downs in Boston, Wonderland Greyhound Park in Revere, Plainridge Racecourse in Plainville and Raynham-Taunton track in Raynham would each add up to 2,000 slot machines, which the state would own.

Five-year licenses bring in $100 million in fees, and the state would take in 60 percent of the slot machine revenue, adding up to about $350 million yearly, according to Morrissey.

The bill would also extend the state's simulcasting law which allows race tracks to broadcast races from other tracks.