Amid the frenzied back-and-forth surrounding their bid for a third Connecticut casino, the Mashantucket Pequot and Mohegan tribes seized some high ground Wednesday, releasing a rendering of the East Windsor facility they hope to build as a hedge against MGM Springfield, the $950 million resort casino under construction in Massachusetts.

Hours earlier, MGM Resorts International, the Las Vegas operator behind the Springfield project, panned the tribes’ plan as a bad deal for taxpayers.

In addition to the rendering, the tribes, partners in an entity dubbed MMCT Venture, touted the benefits of Senate Bill 957, which, they said, would “include a massive infusion of funding to assist the state’s tourism industry.”

The bill, one of two casino-expansion measures the legislature’s Public Safety and Security Committee will air Thursday during a public hearing, would grant the tribes the exclusive right to develop a commercial casino on nontribal land. The tribes’ existing casinos, Foxwoods and Mohegan Sun, are located on their respective reservations and are considered “tribal” rather than “commercial.”

The second bill, House Bill 7239, would require the state to establish a competitive bidding process for choosing a casino operator. MGM Resorts, a big fan of 7239, staunchly has opposed the bill favoring the tribes.

The proposed East Windsor development, which the tribes describe as “a world-class” facility, would encompass 200,000 square feet of space and include 2,000 slot machines and 50 to 150 table games.

“As SB 957 stipulates, the facility would pay a 25 percent tax on its slot machines and a 25 percent tax on its table games, on par with Massachusetts tax rates,” MMCT said in a statement. “The table-game tax rate will be split, with 10 percent of the revenue going directly to the state and 15 percent going to support state tourism initiatives.”

“Under those parameters,” the tribes said, “the bill could add as much as $10 million to the state's annual tourism promotion budget.”

Gov. Dannel P. Malloy’s biennial budget proposal allocates $8.3 million for statewide tourism marketing in each of the next two fiscal years.

The bill also calls for MMCT to pay the state $1 million upfront to cover costs the state would incur in regulating the casino and to make annual payments of $300,000 to the Connecticut Council on Problem Gambling.

“SB 957 is exactly what Connecticut needs to thwart an immediate threat right across our border,” said Kevin Brown, the Mohegan tribal chairman. “What’s more, tourism-boosting provisions make this a statewide bill that will benefit every corner of Connecticut.”

“Tourism is a critical part of Connecticut’s economy, but financial constraints have kept our state from doing all it can to grow this industry,” said Rodney Butler, the Mashantucket chairman. “This bill will be a boon to the many thousands of businesses across Connecticut that rely on attracting new visitors.”

MGM had a different take on SB 957, previewing a presentation an economist it has hired is expected to give at Thursday’s public hearing.

“Economist Nicholas Perna will testify that ‘it is quite likely that both the state and the community (East Windsor) would have been offered larger financial and other benefits if a competitive process had been used,'” MGM said in a statement. “As proof of the impact of a competitive process, in Massachusetts, when Mohegan was seeking a casino license there, the tribe agreed to substantially higher payments not only to the state, but millions more in annual payments to both host and neighboring communities, numbers which far exceed their proposed deal in East Windsor.”

Mohegan Sun failed to win gaming licenses it sought for projects in Palmer and Revere, Mass., in 2013 and 2014, respectively. The projects were resort casinos that were far larger than what the tribes are proposing in East Windsor.

Andrew Doba, a spokesman for MMCT, responded to MGM’s statement, saying that on a per-capita basis, the tribes’ estimated $8.5 million annual payment to East Windsor far exceeds the $25 million MGM has promised Springfield.

Using 2010 population figures, MMCT’s payment to East Windsor works out to $762 per resident, while MGM’s payment to Springfield is equal to about $163 per resident.

"If anyone got a bad deal, it’s Springfield,” Doba said. “Our agreement with East Windsor provides nearly five times more per capita than the agreement reached in Springfield.”

b.hallenbeck@theday.com