State Sen. Cathy Osten, D-Sprague, a reliable supporter of the Mashantucket Pequot and Mohegan tribes’ plan to develop a third Connecticut casino in East Windsor, said Wednesday she doesn’t believe MGM Resorts International has any intention of building a Bridgeport casino.

“I don’t think they have the wherewithal or the authority to complete such a project,” Osten said. “It’s just another way for them to cause more discontent.”

MGM Resorts, the Las Vegas-based operator developing a nearly $1 billion resort casino in Springfield, Mass., announced Monday that it planned to pursue a more than $600 million facility on the Bridgeport waterfront. The project would require state legislative approval and would jeopardize the state’s exclusive gaming agreements with the Mashantuckets and the Mohegans, respective owners of Foxwoods Resort Casino and Mohegan Sun.

Under current law, the state grants the two tribes the exclusive right to operate gaming in the state in exchange for 25 percent of their casinos’ slot-machine revenues. In addition, a law enacted this year authorized the tribes to operate an East Windsor casino in exchange for 25 percent of all the gaming revenue it generates.

Osten, co-chairwoman of the legislature’s Appropriations Committee, also threw cold water on the suggestion that MGM Resorts could press its case with lawmakers during an upcoming special legislative session.

“It’s not going to happen,” she said flatly.

While she expects lawmakers to be called back into session, it will only be to approve a state budget, she said.

The tribes had hoped for federal approval of their amended gaming agreements with the state but appear to have been knocked off stride by the seeming ambiguity of letters they received late last week from a Department of the Interior official.

Michael Black, the department’s acting assistant secretary of Indian affairs, indicated that department action on the amended agreements “is premature and likely unnecessary.” He said “there is insufficient evidence” on which to decide whether the tribes’ new casino would violate exclusivity clauses in the tribes’ agreements with the state.

Gov. Dannel P. Malloy’s press secretary confirmed Wednesday that the governor’s office received the letter from the Bureau of Indian Affairs and is reviewing it.

“The response we received from the BIA will clearly slow down the process,” Chris Collibee said.

Osten said she has seen the letter the tribes received and that she intends to get an interpretation of it from the state attorney general’s office, which also is reviewing it.

In a related development Wednesday, the board of directors of the Greater Norwich Area Chamber of Commerce announced that the organization is opposed to MGM’s Bridgeport casino proposal.

“Another casino in the market threatens the stability of the job market in eastern Connecticut, which in turn affects other sectors of the economy, from businesses to housing, impacting the grand lists of eastern Connecticut towns," Chris Jewell, the board’s chairman, said in a statement.

He said the MGM plan would violate the state’s compact with the tribes, “resulting in the loss of payments to the state in the hundreds of millions of dollars — far above what MGM projects it would pay the state."

The tribes are members of the chamber.

b.hallenbeck@theday.com