Proposition 127, which sought a constitutional mandate for most electric companies to generate at least half of their power from renewable sources by 2030, was defeated by Arizona voters, according to early results.
The Associated Press called the defeat of the proposition before 9 p.m.
The measure was being defeated 69 percent to 31 percent in unofficial results.
Electric companies here spent more than $30 million to convince voters to reject the mandate and leave the issue to the elected commissioners. But supporters, with their own $24 million campaign financed largely by California billionaire Tom Steyer, pointed out that the Arizona standards have been in place since 2006.
The current standard, established by the Arizona Corporation Commission, is for utilities to get to 15 percent by 2025. Other states around Arizona have adopted more aggressive goals.
In Colorado, for examples, utilities have to get to 30 percent by 2020. New Mexico wants its utilities to get to 20 percent by that date, with a 25 percent requirement by 2025 in Nevada and 20 percent by 2025 in Utah.
California already is requiring its utilities to get to 50 percent by 2030.