The state Supreme Court has refused to block a November ballot measure sponsored by Native American tribes that would expand gambling at tribal casinos by allowing in-person betting on sports as well as roulette and dice games.

The initiative, which has qualified for the ballot with more than 1.5 million signatures, was challenged by two legal gambling cardrooms, the Hollywood Park Casino in Inglewood (Los Angeles County) and Cal-Pac Rancho Cordova (Sacramento County).