Her chief of staff appeared at a news conference on the steps of city hall Sunday to announce her position.
Prop 16 is the ballot initiative that would limit the ability of cities and counties to go into the public power business. San Francisco Supervisor Ross Mirkirimi says if the measure passes, it would encourage other corporations to take their issues straight to the voters.
"It is obvious that if PG&E prevails, they will be the first corporation to embed themselves into our state constitution," he said.
PG&E says the power business is risky and complex, and they believe PG&E customers should have a say in deciding whether or not their local government spends money to take on risk.