BOISE, Idaho (AP) – Idaho tribes are demanding that Gov. C.L. “Butch” Otter cease all use of slot-like machines known as instant horse racing terminals because they say the machines are illegal.

In a letter sent to Otter on Tuesday, the tribes said that the betting terminals currently installed around the state do not use pari-mutuel wagering – similar to betting on a live horse race– which is allowed under Idaho law.

The machines installed in Idaho show the last few seconds of a previously recorded horse race on a 2-inch screen. Identifying information about the horse and race is removed so the bettor can’t cheat before making the bet.

The letter, signed by members from the Coeur d’Alene, Kootenai, Shoshone-Bannock and Shoshone-Paiute tribes, called the machines an “illegal hoax.”

“All you have to do is go play them and ask yourself if you are actually betting on a horse race. It’s a hoax that has consistently been found illegal in other states and these machines will continue to make a mockery out of the law until Idaho does something to stop it,” said Chief James Allan, chairman of the Coeur d’Alene Tribe in a statement.

Otter’s office did not return calls seeking comment from The Associated Press on Tuesday.

The letter doesn’t necessarily signify that the tribes are preparing for a lawsuit, but they hope lawmakers work them during the upcoming legislative session to address the issue, Coeur d’Alene Tribe spokeswoman Heather Keen said.

The tribes point out that they have agreed to strict gaming regulations with Idaho, including confining their gaming to reservations and limit the number of machines tribes can have.

Instant racing was legalized in in Idaho in 2013 after horse-industry representatives argued they needed them to save their dying trade. Horse racing has been a steady decline in Idaho, as well as the rest of the nation, because of fewer people attending live racing events and other forms of gambling.

The legality of instant horse racing has been challenged for years. In 2003, Oregon and Wyoming outlawed instant racing machines after the states’ racing commission approved installing them. Yet by 2013, both state legislatures had permitted reinstating the devices.

Proponents say the slot-like machines are saving a dying horse racing industry. Meanwhile, others claim the terminals are cleverly disguised illegal slot machines, which are explicitly banned under Idaho law.

“We play by the rules, and we’re proud that our gaming operations have allowed us to make contributions to better the lives of the people of Idaho. But the potential for limitless, illegal gaming in every county in Idaho puts that at risk in a big way,” Allan said.

The largest collection of instant-racing machines is at Les Bois Park, just outside of Boise. Six months after installing the machines, the track had already gained $1.4 million in profits. In 2011, the track’s net fell short $720,000.