When Gov. Deval Patrick sang a parody of the Foxwoods theme song at Sunday's St. Patrick's Day breakfast, he had some back-up: state Sen. Jack Hart and Reps. Marty Walsh and Brian Wallace.

"Sal, just think, 'bout the wonder of it all," they sang to House Speaker Salvatore DiMasi, the top opponent on Beacon Hill to Patrick's plan to build three destination resort casinos.

Not only were the three supporters of the proposal, but all three lawmakers represent sections of Dorchester that remain heavily pro-union. And Walsh and Wallace, in particular, have emerged as key allies for Gov. Patrick's pro-casino team.

As tension builds at the State House over the plan, with DiMasi and Patrick and their aides trading jabs on a near-daily basis, the all-Democratic Dorchester delegation appears right in the thick of the fight that has consumed the Legislature since Patrick first filed the bill last fall.

Some are strongly in favor of the measure, others strongly oppose it, while some fall in the middle.

Hart is the co-chairman of the Committee on Economic Development and Emerging Technologies, the committee charged with vetting the bill, and has reportedly expressed leanings in support of the plan.

Walsh and Wallace have both taken up the pro-casino banner in the House, fiercely arguing that the plan will bring economic development and benefits. The bill, which would site casinos in western and southeastern Massachusetts, and possibly East Boston, could go before the House as early as this week. Patrick administration officials say the casinos could bring in as much as many as 20,000 jobs, a figure that has fluctuated during the debate, and $2 billion in annual economic activity.

"Ultimately, it's going to mean jobs. A lot of union members live and work in Dorchester," Walsh told the Reporter, adding that the revenues will also lead to more money to be funneled towards police, fire and school departments.

With red shirts reading "Casinos + Unions = Good Jobs," a crowd of union members showed up at the State House's Gardner Auditorium this week to press lawmakers on the bill at the Committee on Economic Development's hearing on the bill.

"I think it's everybody's choice, how you spend your money," said Rahal Adugna, 29, a Dorchester resident who works at a Sheraton Hotel and is a member of Local 26.

Adugna said Dorchester tends to see a lot of crime.

"I think that has to do with not enough good jobs," she said.

Sen. Dianne Wilkerson, who sits on a number of high-profile committees, including the Senate Ways and Means Committee, is a member of the Dorchester delegation who remains unconvinced.

"A revenue plan that requires the poorest people in your state to spend money they don't have to make money for the state is a circular and irrational cycle that really doesn't make a whole lot of sense," she said.

Nor is it a jobs bill, she added. Seventy percent of working-age men and women in her district don't belong to organized labor, she said, and 75 percent of black and Latino males between the ages of 18 and 40 have a criminal record.

"How could this be a jobs bill for this population when the one thing that I can assure you won't happen is that whoever has a CORI [criminal offender records information system] will not be working in a casino?" she said. "The financial benefit, I think, is wholly overstated."

Wilkerson said she also preferred to have the 17,000 seniors in her districts plan for a month to go to a casino out of state, instead of being able to hop on the MBTA's Orange Line.

Other opponents argue that casinos will lead to increased crime, broken families and gambling addiction.

Others fall in the middle or lean in favor. Rep. Willie Mae Allen, whose time at the State House has been the shortest, is still undecided.

Rep. Linda Dorcena Forry said she isn't morally opposed to gaming, since it already exists in Massachusetts through the state Lottery, but added she had concerns about the number of casinos proposed.

"I think three is a lot, especially if we're not going to guarantee that one of them go to the Native American tribe," she said, referencing the Mashpee Wampanoags, who are petitioning the federal government to grant them the ability to open a casino. "So that could really be four."

Forry said she will wait to see what the Committee on Economic Development, which is co-chaired by staunch casino opponent Rep. Daniel Bosley (D-North Adams), will do.

Rep. Marie St. Fleur, a top DiMasi lieutenant through her vice-chairmanship on the House Committee on Ways and Means, did not respond to requests for comment.

But the bill's prospects look dim, with DiMasi and his aides ratcheting up their opposition to the legislation, even as Patrick has brought in the support of unions and local officials, including Mayor Thomas Menino.

Still, casino proponents remained hopeful.

"I think it's kind of unfortunate that the leadership of the House made a determination it's going down before it even has a fair hearing," Walsh said after the St. Patrick's Day breakfast. "I'm still optimistic that we can work something out. There's still a long way to go."