The other shoe is about to drop in California’s protracted and agonizing budget struggle, as voting by mail begins on six controversial measures launched during the endgame of 2009-2010 budget negotiations last February.

For decades, negotiations on the state budget have been hamstrung by requirements for two-thirds legislative majorities both for overall budgets and for tax increases. Democratic majorities fall short of that level, and nearly all Republican legislators reject any tax increase. Last year, as unemployment and home foreclosures soared and revenues sank, legislative talks on how to cope with a $42 billion budget gap remained paralyzed for months.

The compromise that finally unlocked the talks hinged on voter approval of the propositions in a May 19 special election.

Most far-reaching in its consequences, though analysts point out its limited near-term effect on the still-growing budget gap, is Prop. 1A. This complex measure would require using a percentage of General Fund revenues to build up a Budget Stabilization Fund until it totaled one-eighth of General Fund revenues. A highly restrictive spending cap would tie the hands of legislators even when the economy improves. Passage of the spending cap would also trigger extension of several tax and fee measures included in the legislative budget deal.

Prop. 1A reprises Governor Arnold Schwarzenegger’s failed 2005 effort to get voters to approve a state spending cap. Voters again view it with suspicion ― a poll earlier this spring showed opposition at 46 percent, to 39 percent support.

Contingent on 1A’s passage is Prop. 1B, to restore earlier underfunding of education through payments totaling $9.3 billion starting in 2011-12.

Other measures are 1C to revamp the state lottery and allow borrowing against future proceeds, 1D and 1E to redirect funds from voter-approved children’s and mental health programs to other health and human services programs, and 1F to bar pay hikes for legislators or state officers in years of budget deficits.

The California League of Women Voters, which earlier worked with the governor on his redistricting proposal, opposes all six of the May 19 measures. “We oppose these measures because they are not the solution to our long-term financial crisis, with the continuing structural deficit in the state budget and flawed budget process,” LWV president Janis Hirohama said in a statement earlier this spring.

What Prop. 1A will really do, she said, “is tie the hands of the legislature and governor” and “keep them from taking into account the state’s changing demographics and growth in the actual cost of important services like health care.” Hirohama noted that most of 1A’s provisions would not take effect for two years, time she said should be spent “hammering out real solutions” to the budget crisis.

Prop. 1A’s spending cap proposal “will lock in this year’s harmful cuts by locking in current spending levels regardless of growth in need,” the California Budget Project said.

“The system is already a mess, but Prop. 1A will only make it worse,” the California Service Employees International Union said on its web site. “It will guarantee that every year will end in budget disaster, with deep cuts to health care, home care, child care, services for people with developmental disabilities, and more.”

As during the earlier budget talks, Republican Governor Arnold Schwarzenegger and the state’s Republicans are split on the measures. The governor is stumping enthusiastically for all six. At their mid-April convention, the California Republican Party voted to oppose them all.

The complex, interlocking effects of 1A and 1B have also brought about uncharacteristic differences among the state’s labor unions. The California Teachers Association ― the state’s largest teachers’ union ― supports both, while the California Federation of Teachers opposes 1A but backs 1B. The American Federation of State, County and Municipal Employees (AFSCME) opposes all six ballot measures at the state level while one of its locals with many state workers among its members supports them all.