From House Minority Leader Nancy Pelosi to President Obama, Washington politicians are scrambling to get their hands on other people’s toddlers. But they’re not alone.

California has had transitional kindergarten (TK) since 2012-13. Basically, every year since then children must celebrate their fifth birthday sooner and sooner in the year to be eligible for kindergarten. Rather than make a lot of almost five-year-olds wait to start kindergarten, California simply added an entire additional year of formal schooling called “transitional kindergarten.”

The program was controversial from the start.

In 2012, California Gov. Jerry Brown was concerned about the state’s growing preschool and childcare program costs, not to mention the expensive regulatory burden schools were already shouldering thanks to myriad, top-down mandates. He was so concerned he proposed not implementing TK as a mandated program and instead leaving it up to local schools and parents to decide whether to enroll four-year-olds in school.

The state’s Legislative Analyst’s Office agreed, noting that it made no sense to offer an additional year of schooling to a select group of four-year-olds “based on their birth month rather than their academic or financial needs”—especially since districts could allow four-year-olds to attend kindergarten on a case-by-case basis (p. 3, and here).

The 2012-13 state budget ultimately passed with transitional kindergarten funding intact, largely because the projected savings from not implementing the program were lower than anticipated and the budget outlook had improved (see here, here, and here).

Fast forward to 2014. California Senate Pro Tem Darrell Steinberg introduced another “transitional kindergarten” bill to better prepare children for school last week. The Kindergarten Readiness Act of 2014 would require any school district or charter school that offers kindergarten to also offer transitional kindergarten for all four-year-olds. The Kindergarten Readiness Act of 2014 is intended to:

…Make early childhood education in California a rational and efficient system so that all of California’s four-year-old children have access to a voluntary, high-quality transitional kindergarten program one year before enrolling in kindergarten. …More strategically use existing state and federal funds to provide full-day, developmentally appropriate services for four-year-old children from low-income families, and provide high-quality early learning and care to those children who need it the most.

Even if transitional kindergarten were a model of rational efficiency, the following year children would matriculate into a system that could best be described as a portrait of dysfunction (see here pp. 15, 20, and 35; here p. 2).

What’s more, however well-intentioned elected officials may be, much of the “research” they cite about preschool returns on investment, boosting graduation rates, and slashing incarceration rates is deeply flawed.

Decades worth of scientific evidence also shows that government-run preschool does not prime the student learning pump. On the contrary, it shows that any preschool gains begin fading out as early as first grade, and virtually dissipate by third grade—and those findings come from the U.S. Department of Health and Human Services, which oversees the country’s largest and longest-running government managed preschool program, Head Start.

Once a $96.4 million targeted government program for about a half million students, Head Start is now a nearly $8 billion program with nearly 1 million enrollees. Recent official evaluations concluded that the program did not have an overall impact on enrollees (here, p. 3-51 and 9-3); targeted impacts did not last long after the program ended (here, p. 9-4); and by third grade there were no discernable positive program impacts (here, p. xvii; and here, p. 92). The one discernable impact was a lower grade promotion rate for Head Start students by third grade (here, p. xxii); and here, p. 147).

For now, California’s transitional kindergarten plan is voluntary for parents. It also directs schools to allow, “to the greatest extent possible, a parent of an eligible child to choose the transitional kindergarten that the eligible child attends.”

But if history teaches us anything, it’s that small-scale education programs have a tendency to grow into full-blown mandates for one-size-fits all schooling. Gov. Jerry Brown was right to try to keep the program voluntary for parents and schools. He was right to want to voucherize the program to encourage a diversity of programs and providers so parents with limited incomes could find the program that works best for their children. Most important, Brown was right to want to keep parents in charge of their toddlers’ schooling instead of Sacramento educrats and special interest groups.