PG&E Corp. plans to spend $25 million to $35 million on a California ballot initiative that would limit the ability of cities and counties to go into the public power business, the company reported Friday.

PG&E Corp. is the parent company of the Pacific Gas and Electric Co. utility, which is fighting efforts by Marin County and San Francisco to start their own power agencies. Proposition 16, on the June 8 ballot, would force any local governments that want to establish electrical service to win the approval of two-thirds of their voters first.

So far, PG&E has supplied all of the proposition campaign's funding, totaling $6.5 million. On Friday, PG&E took the unusual step of telling its investors that funding for the campaign would affect the company's 2010 profits, lowering them by 6 to 9 cents per share. PG&E Corp. provided the information while reporting its 2009 profit ($1.22 billion, down from $1.34 billion in 2008) and giving its forecast for 2010.

PG&E describes the ballot initiative as a matter of fairness.

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"This is a risky and complex business," said spokesman Andrew Souvall. "We believe that our customers should have a say in determining whether or not their local government spends public money to take on that risk."

The initiative's opponents say PG&E simply wants to block competition.

"It really shows how broken the system is that a corporation can put an initiative on the ballot and spend however much it wants," said Mark Toney, executive director of The Utility Reform Network consumer group.

"We believe that when people realize that this is funded by one corporation to benefit one corporation, the money they spend is going to backfire."

Although Prop. 16 has been denounced by several state legislators and city councils, the campaign against it has raised just $15,500, most of it coming from Toney's organization.

The initiative would affect local governments trying to enter the power business through a new system called community choice aggregation. Under community choice, governments buy electricity on behalf of their residents and set their own electricity rates, while traditional utilities continue to own and operate the power grid.

The initiative also would limit the ability of municipal utilities - such as those in Alameda, Palo Alto and Sacramento - to expand service to new customers.

Marin County officials recently set up California's first community choice system, despite opposition from PG&E. Although state law requires utilities to cooperate with community choice agencies, PG&E threatened not to deliver electricity to the new Marin Energy Authority.

On Wednesday, however, PG&E executives signed an agreement with the authority to deliver power. The authority plans to begin service in May.

"We are pleased that they are now complying with the law," said Dawn Weisz, the authority's interim director.