A $1.5 billion casino resort complex planned for Sterling Forest in Orange County near the New Jersey border suffered a setback after a bistate agency rejected its proposal to build a $20 million highway interchange to get gamblers to the site.

Genting Resorts World, which also operates the Aqueduct slots racino, is the bidder pitching the plan.

Genting wanted to build an interchange off exit 15B of the New York State Thruway at Harriman State Park.

But the Palisades Interstate Park Commission said the request as “not in accordance with our stewardship mission and the public trust to preserve the scenic beauty, natural resources and public enjoyment” of the park.

Genting, in a statement, insisted that the decision won’t torpedo the project because Orange County has proposed to take over Route 106, thus allowing the traffic project to proceed.