Hartford — After a 2-to-1 win in the Senate, proponents of the bill authorizing the Mashantucket Pequot and Mohegan tribes to build a commercial casino in East Windsor turned their attention Wednesday to the House, where the measure’s fate is anything but certain.

“It has a lot of supporters in the House,” Sen. Cathy Osten, the Sprague Democrat, said. “I think it has the ability to come out of there. They may want to amend it, but I’m hoping they won’t. It’s a nonpartisan bill that protects jobs in southeastern Connecticut and around the state. It’s got momentum.”

As expected, the Senate’s southeastern contingent was solidly behind the bill passed early Wednesday morning. Republicans Paul Formica of East Lyme, Art Linares of Westbrook and Heather Somers of Groton joined Osten and 20 other senators in voting for Senate Bill 957. Twelve opposed the measure.

The final vote was taken at 12:35 a.m.

Chairmen of the tribes, respective owners of Foxwoods Resort Casino and Mohegan Sun, promptly issued a statement hailing the vote.

“Today, the Senate took us one step closer to saving more than 9,000 jobs and millions in state tax revenue,” Rodney Butler, the Mashantucket chairman, said. “With the reconfirmation from the BIA in hand, we’re increasingly optimistic that our state’s leaders will rally around our employees like they’ve done for Sikorsky and Pratt & Whitney.”

“We want to thank every senator who voted in favor of Senate Bill 957,” added Kevin Brown, the Mohegan chairman. “The state faces serious financial challenges. This overwhelming, bipartisan vote shows we can be part of the solution.”

Proponents of 957 had gotten boosts in recent days, first when Gov. Dannel P. Malloy said he would sign a bill granting the tribes the exclusive right to develop a third casino, if such a bill reached his desk. He said he would not sign a bill that endangers the state’s existing arrangement with the tribes.

That arrangement calls for Foxwoods and Mohegan Sun to pay 25 percent of their gross slot-machine revenues to the state as long as no other entity is allowed to operate casino gaming in Connecticut.

In a second shot in the arm, state Attorney General George Jepsen’s office indicated that a letter from the U.S. Department of the Interior had eased Jepsen’s concern that the tribes’ third-casino plan and related amendments to the tribes’ compacts with the state could jeopardize the existing revenue-sharing agreements.

“The Department of Interior’s letter appears to affirm that the department’s policy and practice when reviewing amendments is not to disturb the underlying existing relationships among states and tribes,” Jaclyn Falkowski, a spokeswoman for the state Attorney General’s Office, said Tuesday in a statement. “The department does note that the letter is nonbinding. That the department, at least as currently constituted, intends to follow and adhere to that policy should amendments to the agreements between the state and the tribes be submitted for approval does help to alleviate concerns about risk to the revenue sharing agreements.”

MGM Resorts International, the Las Vegas operator whose $950 million casino project in Springfield, Mass., was the impetus for the tribes’ casino-expansion effort, was quick to note that the issue is far from resolved. MGM has urged lawmakers to take a different approach to casino expansion by first establishing a competitive-bidding process among operators.

“The Senate vote is not the final word on casino expansion in Connecticut,” Uri Clinton, senior vice president and legal counsel for MGM, said in a statement. “However, it is disappointing that the state Senate took a vote that denies the state of Connecticut the opportunity to create thousands of new jobs and generate hundreds of millions of dollars in new revenue for the state. Unfortunately, the Senate's bill doesn’t contain a licensing fee for the state, which means that it leaves as much as $100 million on the table in the middle of a real budget crisis."

"Additionally, it doesn’t provide for the real cost associated with infrastructure improvements required to support the proposed casino," Clinton said. "In short, it shortchanges the town of East Windsor, the surrounding communities and the state of Connecticut.”

MGM and other opponents of 957 also have said its granting the tribes the exclusive right to pursue commercial gaming in the state raises constitutional questions that invite litigation. MGM and the Kent-based Schaghticoke Tribal Nation raised such questions in lawsuits they filed over the state’s enactment of a 2015 law that authorized the tribes to form a joint venture and solicit casino site proposals. MGM has pursued an appeal that’s still pending.

Sen. John Kissel, an Enfield Republican, cited the prospect of litigation in casting a vote against 957.

“I have continued to voice my opposition to the establishment of a casino in East Windsor,” Kissel said in a post on his Senate website. “There are some serious legal challenges to this casino, especially as it relates to equal protection, the commerce clause and due process. As a state we should not be opening ourselves up to litigation. This bill could open a Pandora’s box of unintended consequences, including the proliferation of more casinos, especially in Fairfield County.”

Kissel said many families in his district, which is near East Windsor, are concerned about the “adverse impact” they believe the casino would have on their communities.

The Coalition against Casino Expansion in Connecticut, which includes 14 independent groups, expressed disappointment with the Senate vote, noting that the competing casino-expansion proposals “hinge on highly controversial and conflicting economic impact studies paid for by the tribes and MGM, respectively, which ridicule one another as grossly inflated and ignore the economic and social costs of their own proposal.”

“What is most remarkable,” the coalition said in a statement, “is that so many senators were willing to blindly accept the tribes’ study on such a major issue without requiring a comprehensive and independent study of their own or a local referendum on the East Windsor proposal.”

Osten, the senator whose district includes Foxwoods and Mohegan Sun, said the third-casino debate is solely about the need to protect state jobs threatened by the anticipated impact of MGM Springfield, which is scheduled to open next year.

“From the very beginning, all of the talk and planning around another gaming facility in Connecticut has, for me, been about protecting jobs in Connecticut. That’s all,” she said. “There are 140 towns in this state that send residents to southeastern Connecticut every day to work at one of the two casinos there. This is a Connecticut jobs bill, one that protects jobs for middle-class workers, our neighbors, our friends and our family.”

In the 36-member Senate, whose membership is evenly split along party lines, Democrats were more supportive of the bill than Republicans. Fourteen of the 18 Democratic senators voted for it and four against it. Among the Republicans, 10 voted for it, while eight were opposed.

Democrats outnumber Republicans in the House, 79-72.

b.hallenbeck@theday.com