DENVER — Colorado has rejected a proposal to allow casino gambling at a horse racetrack in suburban Denver.

Millions of dollars was spent on the ballot measure, which carries the promise that the taxes raised will funnel $114 million a year to public schools.

The expansion would have applied only to Arapahoe Park in Aurora to start. The campaign was supported by Rhode Island's Twin River Worldwide Holdings, which owns the Arapahoe Park.

Opponents said the measure could hurt revenue at Colorado's existing casinos.

Amendment 68 was the most expensive ballot measure in the nation outside California, with opponents and supporters spending more than $33 million combined.