BOSTON (AP) — Supporters and foes of two high-profile Massachusetts casino proposals made final pitches Monday to local residents in advance of critical votes that could determine whether the projects get off the ground.

Suffolk Downs, a 78-year-old thoroughbred race track, has staked its future on a $1 billion resort casino plan. The track straddles the East Boston neighborhood and the city of Revere and needs referendums to be approved in both communities on Tuesday before it can formally apply to the Massachusetts Gaming Commission for the sole eastern Massachusetts casino license.

Mohegan Sun, which has operated a casino in Connecticut since 1996, is vying for the only western Massachusetts license and was asking voters in the town of Palmer to sign off on a host community agreement for its proposed $1 billion casino and entertainment complex just off the Massachusetts Turnpike.

Both Suffolk Downs and Mohegan Sun have spent years trying to build local support, their efforts predating the 2011 state law that legalized casino gambling. But the lengthy run-up has also given opponents time to mobilize against casinos.

Chip Tuttle, chief operating officer for Suffolk Downs, said he remained ‘‘very optimistic’’ despite a cloud cast by the track’s decision last month to sever a partnership with Caesars Entertainment, the company it had selected to operate the casino. The move came after Suffolk Downs was briefed on concerns raised during the gaming commission’s background check of Caesars.

He said the track was working to notify voters that Caesar’s was no longer tied to the project and that it would soon designate a new operating partner.

The commission separately determined that Suffolk Downs was suitable to pursue a casino license.

The track has not been profitable since 2005, Tuttle said, indicating that the future of the facility could hinge on the outcome of Tuesday’s votes.

Celeste Myers, co-chair of the group No Eastie Casino, said the withdrawal of Caesars brought added ‘‘concern and uncertainty’’ about the project among residents of the tight-knit East Boston neighborhood.

Opponents contend a casino would worsen traffic congestion and hurt small businesses. While foes have been heavily outspent by casino backers, Myers said her group has seen ‘‘an incredible outpouring of support,’’ in recent weeks.

The Palmer proposal is the only one that would be located in a largely rural area of Massachusetts, with supporters pointing to its strategic location between Worcester and Springfield.

Opponents like Iris Carden, 67, say a casino would ruin the community’s rural character by increasing crime, traffic and noise, and even endangering wildlife. She calls casino operators ‘‘blood suckers’’ and questions Mohegan Sun’s claim that the project will generate thousands of jobs for local residents.

‘‘The silent majority has been stepping up to the plate. I think it will be a very close call,’’ Carden said of Tuesday’s vote.

But Jennifer Baruffaldi, spokeswoman for the pro-casino Citizens for Jobs and Growth in Palmer, was ‘‘cautiously optimistic’’ that voters would back the casino, saying the development — which also includes a retail complex and water park — would be a catalyst for economic revival.

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