Boston Mayor Marty Walsh and a group opposed to casinos suggested on Friday that the proposed Mohegan Sun gambling facility is so intertwined with the Suffolk Downs race track straddling East Boston and Revere that residents of both communities should be allowed to decide whether the project should go forward or not.

That’s exactly what happened when Suffolk Downs originally proposed building a casino at the track in partnership with Caesars Entertainment. Revere residents voted in support of that proposal and East Boston residents shot it down. But now that Mohegan Sun is proposing a casino on the Revere portion of the Suffolk Downs track, the gaming operator is insisting that East Boston residents are not entitled to an up-or-down vote on the facility.

Walsh, citing the earlier casino vote by both East Boston and Revere, said denying East Boston host community status on the proposed Mohegan Sun casino is unfair. “First, the casino was 100 percent in East Boston, and the commission named Revere a host community. We can make the case that we’re a host community,” he said.

The Massachusetts Gaming Commission plans to decide on May 1 where the proposed Mohegan Sun and Wynn Resorts gambling establishments are located as part of an effort to clarify the host communities. It would seem a fairly simple question to answer, but the brewing legal fight suggests otherwise. The stakes are high. If East Boston is found to be a second host community for the proposed Mohegan Sun casino in Revere, or if Charlestown is named a second host community for the proposed Wynn casino in Everett, most analysts expect voters in the two Boston communities to vote against them and derail them.

The state gaming law defines a gaming establishment as “a gaming area and any other nongaming structure related to the gaming area and may include, but shall not be limited to, hotels, restaurants, or other amenities.”

The original Suffolk Downs/Caesars casino proposal envisioned the casino as an integral part of the track facility. Since part of the track extended into Revere, Revere was considered a host community. A sliver of the parking for the proposed casino was also located in Revere.

Once East Boston voters rejected the Suffolk Downs/Caesars casino proposal, the horse track shifted gears and leased a section of its property in Revere to Mohegan Sun. Mohegan Sun officials, in a brief filed with the Gaming Commission, said their proposed casino will be located entirely in Revere and divorced from the track.

Matt Cameron, of the group No Eastie Casino, said in a telephone interview that it’s impossible to separate the track and the proposed casino. He noted the proposed Mohegan Sun casino is designed to fit snugly around one end of the track and to give patrons a view of the track. He said the track would have to be considered an amenity to the proposed casino.

In a brief filed with the Gaming Commission, Cameron also said the lease between Suffolk Downs and Mohegan Sun contains a profit-sharing arrangement, suggesting Suffolk Downs and Mohegan Sun have some sort of financial partnership.

Suffolk Downs and Mohegan Sun have refused to release their lease agreement, but James McHugh, one of the five state gaming commissioners, said on Jan. 29 at a commission meeting that he had reviewed it. (See page 142 of the meeting transcript.) He said the lease gives Suffolk Downs no operational control over the proposed casino, “although there is a profit-sharing arrangement and some other things that are typical of a commercial lease.”

McHugh also said at the commission meeting that his initial review indicated the proposed Mohegan Sun casino is located entirely in Revere. “Everything they’ve designed is in Revere, and there are no discernible chunks of the facility in Boston,” he said.

Walsh also wants Charlestown residents to vote up or down on the proposed Wynn casino in Everett, but he made no remarks about that facility yesterday and no one has filed testimony yet disputing Wynn’s assertion that the facility is located entirely in Everett.

Walsh has indicated he may boycott the Gaming Commission’s deliberations on host community status because of what he perceives as commission bias against Boston, particularly by commission chairman Stephen Crosby. The city of Boston has asked Crosby to recuse himself from the process because of statements he made at a recent hearing suggesting his frustration with the city’s tactics.

“My job is to make sure the people of East Boston are protected,” Walsh said on Friday. “The rhetoric about the city upset me. This is a game-changer. There will be no second shot. We have to make sure it’s right the first time.”

Gaming Commission spokeswoman Elaine Driscoll issued a statement on Friday indicating the commissioners would proceed as planned. She said: “The commission’s role is not to participate in or be distracted by the politicizing of certain aspects of this process but instead to remain focused on the mission and challenge at hand: to successfully implement the expanded gaming law in a manner that is participatory, transparent and fair.”