LOS ANGELES -- California voters Tuesday defeated what would have been the country's most aggressive clean power initiative.

The measure would have required the state's utilities to generate half their electricity from windmills, solar systems, geothermal reserves and other renewable sources by 2025.

With 32 percent of the vote counted Tuesday, nearly two-thirds of voters had rejected the measure.

The initiative sparked an odd coalition of critics, including top environmentalists and the state's investor utilities.

Critics charged California's aggressive initiative would have driven up electricity rates, delayed the state's transition to clean power and put small renewable energy companies out of business.

Supporters argued utilities had to be forced to boost their purchases of renewable energy if California was going to clean up the air and slash its greenhouse gas emissions.

"Voters figured out that the environmentally superior result on this was to vote no and to move ahead and really get the problem of more renewables fixed," said David Pettit, a senior attorney, at the Natural Resources Defense Council.

The result was different in Missouri where voters there adopted a mandate requiring the state to produce 15 percent of its electricity from clean energy by 2021. However, that benchmark is still behind California's existing target.

The measure's financing came primarily from billionaire Peter Sperling, whose father founded the University of Phoenix. He has given $9 million to an initiative that environmental groups say is well-intended but poorly drafted.

Pacific Gas & Electric Corp., Edison International and Sempra Energy spent nearly $30 million to defeat Proposition 7.

The large shareholder-owned utilities already are struggling to meet California's current mandate of using 20 percent renewable power by 2010. Municipal utilities, whose renewable programs are voluntary, would have had to comply with the new target had voters approved Proposition 7.

Meanwhile, the alternative fuel measure on the ballot appeared to be losing with early returns counted.

Proposition 10 would give Californians rebates to buy alternative fuel vehicles and set aside money for research.

Critics warned the $5 billion bond measure would steer taxpayer money to Texas billionaire T. Boone Pickens. The natural gas fueling company he founded, Clean Energy Fuels Corp., gave nearly $19 million to bond initiative.

Opponents have raised just $125,000.

With 31 percent of the vote counted Tuesday, roughly 62 percent of voters were rejecting the measure.

It would provided rebates of up to $50,000 for buyers of vehicles that run on natural gas and other alternative fuels. The measure also would set aside money for research.

Supporters have said providing rebates would put less polluting cars on the road and reduce the state's addiction to foreign oil.