California billionaire Tom Steyer is financing a push to mandate increased use of renewable energy in sun-drenched Arizona. The state's largest utility is fiercely opposing the measure.
Clean Energy for a Healthy Arizona aims to ask voters whether they want the state Constitution to require half of Arizona's electricity come from renewable sources like wind and solar by 2030.
The group plans to file more than 225,000 signatures Thursday get the question on the November ballot.
Steyer is financing the initiative through his NextGen Climate Action group, which supported similar efforts in Nevada and Michigan. Only the Arizona measure spawned a political fight.
Arizona Public Service Co. says the proposed constitutional amendment will cause customers' utility rates to skyrocket and harm reliability.
Its parent company, Pinnacle West Capital Corp., spent $1.18 million to oppose the initiative in the first three months of the year.