BOSTON (AP) – The Mashpee Wampanoag have reached a deal to build a resort casino in Middleborough in exchange for at least $11 million in annual payments to the town and $250 million in infrastructure improvements, officials announced Friday.

The announcement comes after weeks of negotiations, and eight days before town voters were scheduled to vote on whether to approve a deal. Casino gambling also still must be approved by the state Legislature.

The deal, the richest ever between a sovereign tribe and a local government, bests the tribe’s original offer by adding $4 million to the town’s annual payment and $100 million in infrastructure improvements.

“I will say the negotiations were tough, they were tough,” said tribal chairman Glenn Marshall. “We’re just hoping everybody is now ready to go to work as far as the commonwealth is concerned.”

Clyde Barrow, a University of Massachusetts-Dartmouth professor who studies the gambling industry, said it’s a good deal for Middleborough, though he thinks the town should have negotiated for a percentage of annual gross gaming revenues.

Barrow said the focus of the gambling debate now is squarely on Gov. Deval Patrick, who has commissioned a task force to study expanded gaming in the state. The panel is expected to report by summer’s end.

“This whole thing could die if the governor comes out against it, so I think it really puts the spotlight on the governor from this point forward,” Barrow said.

Patrick’s office did not immediately respond to a request for comment.

Negotiations began after the tribe officially received federal recognition in May after more than three decades of fighting for it. The tribe has purchased 125 acres of town land, has an option to buy another 200 contiguous acres and has approached another land owner about a 200-acre abutting tract.

Talks between the tribe and town looked to be in trouble after town officials asked for millions more than the tribe offered in its original proposal. Marshall wrote that Middleborough officials had become “unnecessarily hostile.”

But selectman Adam Bond, one of the town’s negotiators, said there was a breakthrough once the sides understood they had much in common, including long histories and a desire to achieve financial independence.

“We changed philosophies, all of us, from negotiating this as just sort of a lifeless contract, where each side tries to beat the other down,” he said.

Scott Ferson, a spokesman for the tribe, said both sides realized they weren’t competing businesses, but partners. “The tribe believes that success shouldn’t rest exclusively with the tribe,” he said.

The bulk of the $250 million in infrastructure improvements – $172 million – would go to transportation upgrades, but the money would also pay for improvements in the natural gas, electric, water, wastewater and sewer systems.

The $11 million annual payment includes a $7 million base payment that was part of the tribe’s original offer, plus a projected $4 million annually from a 4 percent lodging tax on the proposed casino complex’s 1,500-room hotel. The base payment will increase at least 3.1 percent annually, depending on inflation.

The deal also includes $2 million up front to buy new police cruisers and ambulances, and to fund new police and firefighters needed if a casino comes to town.

Barrow said 2010 was the earliest a casino could open, assuming there’s quick approval from lawmakers. There’s support for expanded gambling in the Senate as well as the House, even though speaker Sal DiMasi has expressed concerns about expanded gaming.

It’s all moot if Middleborough, a town of about 20,000, rejects the deal during a July 28 town meeting vote. Residents have worried about a casino’s social costs, as well as seeing their town’s identity swallowed by a huge gambling complex. Bond said Middleborough will never just be a place that hosts a casino.

“Not a chance,” he said. “This town is pretty strong in character.”