East Windsor — State, tribal and local leaders reasserted their commitment to the proposed third Connecticut casino here Monday, donning hard hats, vowing to take the fight to the lingering naysayers and cheering as demolition equipment knocked a hole in the side of a vacant Showcase Cinemas building.

It will take six weeks to demolish the structure, by which time the Mashantucket Pequot and Mohegan tribes hope to have cleared up a legal entanglement that has threatened to derail the project.

"There’s nothing to stop construction,” Rodney Butler, the Mashantucket chairman, told reporters following the ceremonial start of demolition at the casino site, off Exit 45 of Interstate 91.

“The federal government has no control over our ability to proceed,” added Kevin Brown, the Mohegan chairman.

Tied up in court is a federal lawsuit the tribes and the state have lodged against the U.S. Department of the Interior seeking to compel approval of amendments to the state’s gaming agreements with the tribes, respective owners of Foxwoods Resort Casino and Mohegan Sun.

Butler said the East Windsor casino, a smallish facility carrying a price tag of about $300 million, could be open within two years — some 20 months after construction commences.

That would be well after the scheduled September opening of MGM Springfield, the nearly $1 billion resort casino that MGM Resorts International is building in Massachusetts, 12 miles north of the East Windsor casino site.

Numerous speakers at Monday’s “demolition ceremony” took aim at MGM Resorts’ efforts to stop the East Windsor project. State Sen. Cathy Osten, a Sprague Democrat, was particularly emphatic, calling the Las Vegas-based operator’s lobbying tactics “disrespectful.” She said “not one thing was right” about MGM’s efforts to block the East Windsor casino while proposing to pursue an alternative project in Bridgeport.

“They’ve been here before and they’ve lied to Connecticut residents,” Osten said, a reference to MGM’s former licensing agreement with Foxwoods, which named its second hotel tower MGM Grand at Foxwoods in 2007. Years later, when MGM Resorts landed the western Massachusetts casino license, it withdrew from its relationship with Foxwoods. The casino’s second tower is now The Fox Tower.

“If the Department of Interior doesn’t want to work with us, we don’t want to work with them,” Osten added.

At that point, East Windsor First Selectman Robert Maynard offered to let Osten swing a mallet at the theater building standing nearby.

While Monday’s event seemed intended to reassure supporters that the project is on track, opponents continue to do their best to raise doubts. On Thursday, the state legislature’s Public Safety and Security Committee is scheduled to take testimony on a number of gaming-related bills, including one that would establish a competitive-bidding process for a casino on nontribal land while at the same time repealing authorization for the East Windsor project. Legislators from the Bridgeport and New Haven areas have pushed for the bill, which has MGM Resorts’ backing.

State Sen. Tim Larson, an East Hartford Democrat whose district includes East Windsor and who co-chairs the committee, said he gives the bill little or no chance of advancing.

“I have no idea where it came from,” he said. “I don’t think it’s going anywhere. I know I’m not going to bring it up in the Senate. … And I don’t think MGM has any intention of building a casino in Bridgeport.”

Butler and Brown announced during the ceremony that the East Windsor casino will help save 4,300 jobs in Connecticut that could otherwise fall victim to competition from MGM Springfield while creating at least 650 jobs in the Greater Hartford area, including 325 jobs in Hartford, 150 in East Windsor and another 175 jobs throughout East Windsor, Windsor Locks and surrounding communities.

“Getting this project up and running in East Windsor is critical to ensure that Connecticut’s casino industry continues to offer its gaming residents a high-quality experience provided by highly skilled and competent employees,” said Beverley Brakeman, a regional official of the United Auto Workers, a union that represents some 1,500 table-games dealers at Foxwoods.

The East Windsor project will put some 2,300 men and women in the building trades to work as well, according to Dave Roche, president of the Connecticut Building Trades.

Lieutenant Gov. Nancy Wyman, who spoke at Monday’s event, quipped that she hoped the East Windsor casino would have a job for a certain woman from Tolland, where she lives. She said she may need a job next year when her term is up. She is not seeking re-election.

At 2:58 p.m., the teeth of a backhoe bit through the wall of the old theater building.

b.hallenbeck@theday.com