Buoyed by the General Assembly's passage of their third-casino bill, the Mashantucket Pequot and Mohegan tribal chairmen said Thursday they'll press ahead with construction of an East Windsor facility despite the prospect of legal action aimed at stopping it.

"We're not going to be swayed by these threats of litigation," the Mohegans' Kevin Brown said. "There is not a good foundation here for an injunction."

While lawsuits raising constitutional arguments could take years to resolve, it could take a court order to derail the project at this point, observers have said.

Brown and his Mashantucket counterpart, Rodney Butler, conducted joint phone interviews Thursday in the wake of their legislative victory, which was years in the making. Early in the morning Wednesday, the last day of the legislature's regular session, the House of Representatives overwhelmingly endorsed Senate Bill 957, authorizing the East Windsor casino. The Senate had backed it two weeks earlier.

MGM Resorts International, whose Springfield, Mass., casino project was the impetus for the legislation, had lobbied hard for an alternative bill calling for a competitive-bidding process that eventually could have led to the licensing of a third Connecticut casino. Having sued the state over a 2015 law that enabled the tribes to form a partnership and to solicit third-casino proposals, MGM vowed to "continue to vigorously advocate in the courts."

The Kent-based Schaghticoke Tribal Nation also promised to sue once Gov. Dannel P. Malloy, as expected, signs Senate Bill 957.

"There's been this suggestion that the process was not transparent, but this has all been waged out in the open for the last two years, and it's a good deal, as evidenced by the bill's passing and the BIA letter," Brown said.

That letter, written last month by a U.S. Department of the Interior official, affirmed the department's view that the tribes' joint ownership of a commercial casino would not affect their existing exclusivity arrangement with the state. The arrangement calls for the tribes to pay the state 25 percent of the slot-machine revenues generated by their existing facilities, Foxwoods Resort Casino and Mohegan Sun.

The department's Bureau of Indian Affairs officially must approve the final versions of the amendments before the tribes can proceed with the East Windsor project.

"We're moving on multiple tracks," Brown said. "There's a lot of design work to be done that will be measured in weeks. We'll work simultaneously with East Windsor zoning officials to make sure we fit within the parameters of the town's regulations."

Butler said the casino could be open in 18 to 24 months, or "shortly" after MGM Springfield's scheduled September 2018 debut.

"We'll get it open as close to MGM's opening as possible," he said. "The benefit we have is two tremendously well-known brands and our databases of thousands of customers. We want to keep those people."

Butler said the tribes were only "loosely" involved in negotiations that led the House to draft a second gaming-expansion bill designed to garner support for SB 957. The so-called "sweetener," passed by the House and Senate, authorizes additional off-track-betting locations, establishes an advisory panel to coordinate bookings at certain entertainment venues and requires the state to prepare for the possible legalization of sports betting.

"Obviously, it's our area of expertise, but it wasn't our idea," Butler said. "Sports betting is a federal issue, so approval of that is going to take some action in Washington. We think it's a good concept. Other jurisdictions are doing it."

"We're interested," Brown said.

The chairmen noted that their tribes, whose existing casinos are fierce competitors, are now bound tight as business partners.

"This was just the exclamation point on our (two tribes') relationship," Butler said. "We've been working together for a long time."

But, Brown acknowledged, they came together as never before to "defeat the interloper from the outside."

He quoted a Bedouin proverb: "I against my brother, my brothers and I against my cousins, my cousins and I against strangers."

b.hallenbeck@theday.com