Incoming Arizona Senate President Bob Burns, R-Peoria, and Rep. Steve Yarbrough, R-Chandler, talked publicly Tuesday about a painful political subject that has been obvious to budget watchers for months — the state will have to cut K-12 education funding to deal with billion-dollar deficit woes.

K-12 education is the state’s single largest expenditure out of the $10 billion General Fund. At $4.25 billion, K-12 education takes up nearly 43 percent of everything spent from state taxes and is twice as much as the next highest expenditure, the state’s portion of Medicaid health insurance.

Wipe out the “rainy day” fund, crank up agency fees and pull all of the accounting gimmicks you want. The scope of the Arizona’s deficit problems are so big — $1 billion last year, $1.2 billion this year, more than $2.2 billion next year — there’s no way to stop the red ink while declaring K-12 education untouchable. (Unless you are talking about tax increases, but you’re going to talking to yourself because no one else will be listening.)

But K-12 education largely avoided any budget cuts earlier this year because of a lingering public perception that Arizona leaders didn’t commit enough resources in the past, a political backlight that Gov. Janet Napolitano used to great advantage to protect such funding. There’s also the sales tax for education approved by voters in 2000. One provision of that law says the state must increase basic state aid to school districts by 2 percent each year. Technically, the law says the increase must be applied to basic state aid OR transportation funding (a far smaller cost). But Napolitano and the education establishment have successfully argued the Legislature would face a backlash hurricane if it adopted a narrower interpretation that says basic state aid can be slashed.

However, a new budget summary from the Joint Legislative Budget Committee says at least $2.2 billion in K-12 education funding isn’t protected in any way by that 2000 law, if you include the property taxes collected by local school districts. Unless someone gives a compelling legal argument otherwise, that would give state lawmakers quite a bit of discretion to temporarily roll back education spending.

Napolitano would fight such cuts to the bitter end. But everyone expects her to be going to Washington soon, and Secretary of State Jan Brewer to move into the governor’s office. So Brewer’s fellow Republican leaders can talk more openly about what they believe inevitably has to happen to meet their constitutional mandate to balance the state budget.