New Jersey doesn’t have the money to fully fund its public schools, the funding formula is distorted and unfair, and each year there’s a desperate struggle to come up with tolerably acceptable state and local education budgets.

So what do some legislators want to do? Poke another hole in the sinking ship.

State senators are pushing again to require every district to offer full-day kindergarten and every child age 5 by Oct. 1 to attend kindergarten.

About four out of five school districts in the state already offer full-day kindergarten, mostly by choice. The lower-income Abbott Districts already are required to offer it, and the state funds it for them as a result of a lawsuit.

As they did two years ago, the legislators and their teacher union allies are making questionable claims about the effectiveness of full day compared with half day kindergarten. They cite the support for it by the National Education Association teachers union. The NEA says, “Full-day kindergarten can produce long-term educational gains, especially for low-income and minority students,” based on analysis by the Education Commission of the States.

In contrast, a report on the advantages and disadvantages of full-day kindergarten by the Wisconsin Department of Public Instruction says, “The long-term effects of full-day kindergarten are yet to be determined,” although strong academic advantages are seen as much as a year later.

The arguments are similar to those made for publicly funded preschool, as is the lack of solid evidence. Last year, the Brookings Institution’s Pre-Kindergarten Task Force said, “Convincing evidence on the longer-term impacts of scaled-up pre-K programs on academic outcomes and school progress is sparse, precluding broad conclusions.”

Critics of more kindergarten and preschool say much of it amounts to an expensive form of daycare for young children. The N.J. Child Care Association has said mandated full-day kindergarten would “burden the entire tax base with increased taxes forever, in order to relieve some families of a temporary cost.”

Against the questionable benefit of full-day kindergarten are a couple of obvious disadvantages. New Jersey already has the highest property taxes in the nation. And the state already can’t afford existing school programs, having cut aid to some South Jersey districts by 2 percent for this school year. And when state leaders finally agreed to increase aid for others by $150 million to get a budget passed, they needed a financial trick — putting off reimbursing towns for Homestead property tax credits — to fund that.

The state needs major changes to how it funds schools and a massive money-saving consolidation of its 599 school districts to as few as the state’s 21 counties.

Once that is done, it might be time to consider the merit of new spending on education programs.

For now, giving money to possibly beneficial programs is just taking it away from proven and unfunded education needs.