Some fissures have emerged within the once-unified New Jersey sports betting movement.

Gov. Phil Murphy’s Racing Commission, which had been working hand-in-hand with Monmouth Park and other facilities to overturn a national ban on sports betting — and quickly bring sports betting to the Garden State — is now threatening to sue any casino or racetrack that dares to open as the governor ponders when he will sign the necessary legislation.

Monmouth Park operator Dennis Drazin and other racetrack owners were told that disciplinary action would be taken and that their suitability for licenses could be jeopardized if they didn’t comply.

“The Commission is aware of certain public statements contemplating the commencement of sports wagering at racetracks in New Jersey prior to the enactment of new enabling legislation. Please be advised that no activity related to sports wagering may take place on the grounds of a racetrack unless the persons and entities involved have filed an application and obtained a vendor’s license,” Racing Commissioner Frank Zanzuccki said in a letter, which was received by racetrack officials Thursday and reviewed by The Post.

“Participation in sports wagering, or in services related to sports wagering, on the grounds of the racetrack without first obtaining the necessary license will result in the Commission taking disciplinary action against that person or entity.”

Zanzuccki then made another not-so-veiled threat.

“Additionally, as you may be aware, both houses of the Legislature has passed comprehensive legislation requiring the issuance of a sports wagering license by the Commission and the regulation of sports wagering by the Division of Gaming Enforcement, which legislation is now under consideration by the Governor. The conduct of sports wagering related activities by persons or entities prior to the final passage of this legislation may bear upon their suitability for licensure under the anticipated law.

“It should be fully understood that any improprieties or adverse conduct related to any unregulated activities would have the potential to jeopardize their ability to be licensed for sports wagering under the new law,” the letter continued.

Monmouth Park’s Drazin told The Post Friday morning that he was unlikely to begin sports betting Friday.

“I can’t answer that yet, but probably not,” Drazin said. “I’m waiting to have a discussion [with Zanzuccki] before I react.”

Drazin was expecting the governor to immediately sign the bill into law and then get a temporary sports betting license from Zanzuccki’s commission.

Murphy is said to be holding up the bill so he can use it as leverage in budget negotiations, according to sources close to the situation. He has 45 days to sign or veto the bill, or it will automatically turn into law.