TRENTON, N.J. — New Jersey’s horse racing industry is asking the U.S. Supreme Court to consider whether the state can allow sports betting at its racetracks and casinos.

Thoroughbred horsemen, who operate Monmouth Park in Oceanport, say they’re missing out on millions of dollars because federal law bans such wagering in all but four states.

The 3rd U.S. Circuit Court of Appeals in August invalidated a law passed by New Jersey in 2014 that would have allowed sports betting at casinos and racetracks. The court found New Jersey’s law repealing prohibitions against sports gambling violated the 1992 Professional and Amateur Sports Protection Act, which forbids state-authorized sports gambling.

“Because PASPA, by its terms, prohibits states from authorizing by law sports gambling, and because the 2014 law does exactly that, the 2014 law violates federal law,” the court wrote.

The Supreme Court declined to take the case after it was petitioned in 2014.

Currently, only Nevada offers legal sports betting on individual games. Delaware offers multigame parlay betting in which players must pick several games correctly to win. Both were given exemptions when PASPA was passed.

New Jersey Gov. Chris Christie and supporters in the state Legislature have sought to legalize sports gambling to help prop up the struggling casino and horse racing industries. It’s estimated up to hundreds of billions of dollars are bet illegally on sports every year in the U.S.

New Jersey voters approved legal sports gambling in 2011.

The state has not decided whether to join with the horsemen, said Lee Moore of the attorney general’s office.