State officials Monday will release a long-awaited request for proposals to develop Belmont Park with retail, entertainment, sports and hospitality options — leaving the door open for an expected bid by the New York Islanders to return to Nassau and construct a new hockey arena.

The RFP, obtained by Newsday, provides developers less than two months to place a bid to develop up to 43 acres of vacant land at the state-run park in Elmont.

“Belmont Park represents an exciting and much-anticipated development opportunity on Long Island,” said Howard Zemsky, president and chief executive of Empire State Development, the state business agency that will evaluate the bids. “We encourage respondents to submit creative proposals that stimulate vibrant community and economic growth in the region.”

Among the expected, and most high-profile bidders, are the Islanders, who are considering opting out of a 25-year license agreement to play at Barclays Center in Brooklyn after only two seasons.

The RFP stipulates that among the potential recreational uses that would be considered are sports fields and an “indoor recreation facility.”

NHL Commissioner Gary Bettman told reporters in April that the Islanders believe there is a “terrific opportunity” to build a new arena at Belmont.

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The Islanders, which already have renderings of a potential Belmont arena in anticipation of their bid, are being advised by Oak View Group, a sports arena development company backed by Madison Square Garden. The team also has discussed joining up with Sterling Project Development, the majority owners of the New York Mets, on investing in and developing a new arena, sources said.

The Islanders and Barclays management, both of which declined to comment on the RFP, can opt out of their agreement in January.

Belmont, which first opened in 1905 and was last redeveloped 50 years ago, is considered among the Island’s most valuable real estate, with dozens of acres of underutilized parking lots bordering the Cross Island Parkway and a seasonal-only Long Island Rail Road spur. The New York Racing Association plans to upgrade the existing park facilities next summer.

Last year, ESD scrapped all proposals to redevelop Belmont, including a 25,000-seat soccer stadium for the New York Cosmos, after a long-delayed four-year process.

The new RFP is similar to that 2012 request in that it includes the same two parcels for potential development — 28 acres south of Hempstead Turnpike close to the grandstand and 8 acres west of the Belmont Park clubhouse that borders the LIRR station.

While respondents must bid on both parcels, they also can propose an alternative development that includes an additional 7 acres north of Hempstead Turnpike.

“The goal of the RFP is to strengthen Belmont as a premier destination for entertainment, sports, recreation, retail and hospitality on Long Island,” said Robert Williams, chairman of the state’s Franchise Oversight Board, which monitors NYRA and approved the release of the RFP on Friday during its meeting in Albany.

All bid proposals, the RFP states, must be “complementary” to the existing racetrack, maximize economic benefit to the state, use environmentally friendly design practices, feature “meaningful” participation from minority, women and veteran-owned businesses, provide jobs for area residents and benefit the surrounding neighborhoods of Elmont and Floral Park.

“Respondents must list community amenities that will be included in the project as well as a detailed plan for community outreach,” the RFP states. “Given the sites are adjacent to an existing residential community, it is important to detail how the project will be integrated into the surrounding fabric.”

Tammie Williams, a trustee of the Elmont Public Library and a member of the Elmont Parkhurst Civic Association, said developers should engage with the community as they prepare their bids.

“We should not limit ideas to stadiums or arenas but rather [encourage] as many creative proposals as possible,” Williams said.

State Sen. Todd Kaminsky (D-Long Beach) said the RFP appeared broadly written to include a host of potential bidders. He added that the “Belmont community looks forward to reviewing exciting and innovative proposals, and expects to have their voices heard as this process moves forward.”

Proposals that include residential development, casino games, video lottery terminals or simulcast wagering will not be considered, the RFP states.

“It is time for the untapped potential of Belmont Park to be realized and for ESD to review proposals that will enhance the existing horse racing industry while bringing new jobs and opportunities to Long Island,” said state Sen. Elaine Phillips (R-Flower Hill).

The winning bidder must provide the state a check for $1 million to be used by ESD and the Franchise Oversight Board for legal and consulting costs.

All bids are due by Sept. 28.

With Jim Baumbach