The existing supermajority requirement for local bond approval goes back to the series of tax restrictions in California’s Constitution inaugurated by the passage of Proposition 13 in 1978.

Because of a prior ballot measure, the threshold for approval for local school construction bonds already has been lowered to 55%.

If Proposition 5 passes, it would affect all future local bond campaigns covered by the measure, including those concurrently on the November ballot.

Most notably, Bay Area officials are asking voters in November to approve a $20-billion bond to finance various affordable housing programs in that region, the largest housing bond in the state’s history. Proposition 5’s approval would mean that the Bay Area measure would need the support of only 55% of voters to pass rather than two-thirds.