As plans for the MGM Springfield casino continue to diminish in scope, Connecticut’s two sovereign Indian tribes are moving forward with efforts to maintain their market share through a satellite casino in the north central part of the state.

The MGM casino, which was originally slated to be completed in 2017 at a cost of $800 million, has now been reduced by 122,534 square feet and is not expected to open until fall 2018.

According to Masslive.com, a “notice of project change” filed recently with the Massachusetts Executive Office of Energy and Environmental Affairs by MGM detailed a 38.1 percent reduction in retail space along with a smaller movie theater and bowling alley. Space for gaming and convention space will remain similar to the original proposal. The changes follow revisions last month that did away with a 25-story hotel tower in exchange for a six-story horizontal layout with the same number of rooms, Masslive.com said.

To combat the looming threat, the Mashantucket Pequot Tribe and the Mohegan Tribe last month formed a joint business venture authorized by the state legislature allowing them to enter into conversations with municipalities interested in hosting their vision for a smaller-scale gaming operation in the Hartford area.

Estimates from the tribes and Pearce Real Estate, the firm handling the request for proposals open to interested municipalities, indicate the casino will be between 150,000 to 350,000 square feet and will house more than 2,000 slot machines and roughly 100 to 150 gaming tables.

A spokesperson for the tribes said they have not received any proposals to date but would not expect to see a response until much closer to the deadline. Municipalities must respond to the RFP by Nov. 6 to be considered as a possible site. A final decision will be announced by Dec. 15.

A consultant hired by the two tribes said a $300 million casino in north central Connecticut would generate $300.9 million in gross gaming revenue and create more than 2,000 jobs. Failing to build a new casino to ward off competition from MGM and other casinos means the state would stand to lose about 9,300 jobs total by 2019, according to the same study.

The Hartford Courant reported that East Hartford Town Council voted Tuesday to authorize a proposal that would put the city in contention to host the new casino.

Last month, East Hartford’s planning and zoning commission unanimously approved a special permit to use the former Showcase Cinemas on Silver Lane for “restaurants, office space and entertainment” at the request of developer Anthony W. Ravosa Jr., according to meeting minutes. Ravosa is a former Springfield City Councilor.

Further north, the Associated Press reported that Windsor Locks First Selectman Steven Wawruck Jr. is entertaining the idea of working with the Connecticut Airport Authority to bring the casino to Bradley International Airport.

Wawruck said the airport authority’s executive director, Kevin Dillon, has been invited to speak at a meeting of the town’s board of selectmen next week and that a town vote would be required if the tribes ultimately chose Windsor Locks as the location for their new casino, according to the Associated Press.

Asked about a casino at the airport, Gov. Dannel P. Malloy said Wednesday that he’s “neither endorsing or panning their response to a public RFP.”

He said he doesn’t know whether it makes sense or doesn’t make sense. That’s why the state has an authority.

Meanwhile, further to the north, the Enfield Square Mall has been bandied about as a potential site for the new venture, Enfield residents who turned out for a “casino community conversation” on Oct. 1 were largely opposed to the idea.

MGM has moved to quash the tribes’ plans through a federal lawsuit alleging that the Connecticut’s new law allowing the tribes to form the joint business venture and negotiate with municipalities is unconstitutional because it “is a race-based set-aside in favor of the two Preferred Tribes at the expense of all other tribes, races, and entities.”

A pending motion filed by the state of Connecticut on Sept. 23 to dismiss the lawsuit was met with an amended complaint by MGM on Oct. 5.

The motion to dismiss claimed the state is not showing favoritism and that nothing in the existing law precludes MGM from developing a casino in Connecticut – though it adds that Massachusetts licensing forbids the company from building a casino within a 50-mile radius of Springfield, which rules out much of Connecticut. It also claims that the law does not authorize a third casino; instead, such approval is contingent on passage of a separate law in the future.

MGM’s amended complaint reiterated its argument that Connecticut’s law puts other developers “at a competitive disadvantage” because it has already fast-tracked the tribes’ efforts through the explicit endorsement of an RFP process restricted to the tribes only.

The state is expected to file another motion to dismiss the amended complaint by Oct. 29, according to court documents. Opposition to that motion will then be filed by Dec. 2 and any replies should be filed by Dec. 23.