MIDDLEBOROUGH, Mass. – Middleborough officials, under fire from some residents who say a tentative deal that would bring millions of dollars to the town if the Mashpee Wampanoags build a casino is not enough, are now planning on demanding much more from the tribe.

The revised agreement circulating among town leaders and reviewed by The Boston Globe, would seek upfront payments of at least $250 million for infrastructure improvements as well as a percentage of the casino’s annual slot machine revenues.

The town has been offered up to $150 million for road, water and sewer upgrades and $7 million annually for 10 years.

A cut of the slot revenue as low as 1 percent or 2 percent could add up to much more than the flat $7 million offer, especially if the tribe follows through on plans to add thousands of slot machines in the first years of operation. Casino slot revenue of $1 billion annually could mean between $10 million and $20 million per year for the town.

That would be on top of the 25 percent of slot revenue the state is likely to demand.

Tribal leaders have not been sent the new proposal yet, but a Mashpee Wampanoag spokesman has said that the first offer is not subject to negotiation.

In another casino development, a gambling tycoon who grew up in Boston recently had a meeting with an official from Gov. Deval Patrick’s administration, according to the Boston Herald. Sheldon Adelson, chairman and CEO of the Las Vegas Sands Corp., met with Secretary of Housing and Economic Development Dan O’Connell, spokeswoman Kofi Jones said.

“He came in and offered his ideas on how the commonwealth could benefit from expanded gambling,” Jones said. “He addressed some of the economic impacts associated with the gaming industry. We met with him as we have met with people on all sides of the issue and continue to.”

Middleborough’s revised proposal was drafted by two lawyers hired by the town specifically to deal with casino issues, including Dennis Whittlesey of Washington, D.C.

In exchange for financial considerations, the town would support the tribe in getting state and federal approval for a casino.

The 36-page revised agreement would help the town of 20,000 residents 40 miles south of Boston deal with financial problems, including a $4 million deficit in the town’s $64 million budget.

Clyde Barrow, a casino researcher at the University of Massachusetts-Dartmouth, called the original agreement “a bad deal for Middleborough, its residents, and the town’s future tax base.”

The revised proposal calls for $172 million for road improvements; $26 million for electrical upgrades; $10 million in gas system expansion; $22.5 million for water service and satellite wells; $26.3 million for wastewater system improvements; and $8 million to $10 million for a new police station.

The town also wants the tribe to underwrite the cost of a new police cruiser, two new ambulances, four additional police officers, and additional staff for other town departments.

The tribe would also be required to compensate abutters who can prove the casino has lowered property values and contribute to a gambling addiction treatment facility.