An opposition campaign chaired by former Republican Gov. Frank Keating relied heavily on law-enforcement officials to make the case that recreational legalization would open up the state up to even more criminal behavior and endanger kids.
The Associated Press called the contest with roughly two thirds of precincts counted and the petition failing by a more than 20-point margin.
The rejection of the Oklahoma referendum marks the latest ballot failure for legalization advocates in recent months. Voters in Arkansas, South Dakota and North Dakota defeated legalization referendums in November, while voters in Maryland and Missouri approved adult-use legalization petitions.