In a blow to the Mashpee Wampanoag tribe, the Gaming Commission opened the state’s southeast region to the possibility of a commercial casino yesterday, unwilling to risk lengthy delays as the tribe tries to secure federal approval.

“What it means is we’ve made a decision on how to proceed,” said Gaming Commission Chairman Steve Crosby. “Either way, southeastern Massachusetts will either proceed with a tribal casino or a commercial casino, but it won’t be left in the lurch.”

Commissioners voted unanimously to allow commercial casinos to essentially compete with the tribe on that turf. But gaming officials pointed out they could still consider the tribe at any point in the process.

Crosby said it’s all about getting casinos open in a timely fashion.

“The tribe insists they’ll get it this year or the beginning of 2014,” Crosby said. “Other people say it’ll take years. And some people say they’ll never get it because of all the legal impediments. There’s simply no way for us to know with any degree of certainty what will happen there.”

But the tribe, which launched new TV ads earlier this week portraying the commission as all-powerful, blasted the decision, calling it “misguided.”

“At a time when we need to create thousands of jobs in every corner of the state and put people back to work, this is a major step backwards,” said Tribal Chairman Cedric Cromwell in a statement. “Over the last 400 years, the Mashpee Wampanoag Tribe has experienced a long succession of broken promises by the government, from the loss of our land, our personal freedom, and our aboriginal rights, to name just a few.”

The tribe is in the process of securing federal land in trust and hopes to build a casino in Taunton.

“Today’s vote by the Massachusetts Gaming Commission does not change the process for the Mashpee Wampanoag Tribe, or our cooperative effort to create new economic development and job creation opportunities in the region,” said Jason Lefferts of the state’s Executive Office of Housing and Economic Development.