The nation's largest public pension fund lowered its forecast Wednesday for investment returns and asked the state of California, school districts and local governments to increase contributions a move that could siphon more money from basic services.

The nation's largest public pension fund voted Wednesday to lower its estimate for annual investment returns, meaning it will need more money from the state, school districts and local governments to maintain its ability to fund promised retirement benefits.

Two dozen city and county governments in California face a combined $135.7 billion in unfunded pension liabilities, according to a study released Tuesday also found the problem is growing.

Facing another budget deficit and the prospect of deep cuts to education, Gov. Jerry Brown plans to file a ballot initiative as early as Friday that asks voters to increase taxes on the wealthy and raise the sales tax by half a cent.

A study released Friday by a pension-reform group suggests California state and local governments could save billions of dollars a year by moving to a hybrid retirement plan similar to one used by the federal government.

California was scheduled Tuesday to borrow about $5 billion from private investors as a hedge against a possible default by the federal government.

California's controller took the rare step Tuesday of halting paychecks for all 120 state lawmakers after he determined they failed to meet a voter-approved requirement aimed at getting the Legislature to approve balanced budgets on time.