Every great idea and good intention runs into reality, eventually.

And by “reality,” I mean “So, who pays for this?”

This is where advocates working to get more low-income Pima County kids into high-quality preschool find themselves. It’s a frustrating place to be, convinced of the utter necessity of the goal but reliant on others to make it happen.

It’s especially frustrating when those “others” are elected officials and government agencies confined by myriad rules, statutes and political realities.

For months now, a tight mix of business leaders, educators, early childhood experts and community members, calling themselves the Early Childhood Working Group, have been working to solve an urgent problem:

Only 24 percent of Pima County’s 3- and 4-year-olds with family incomes below 200 percent of the federal poverty level (about $42,000 for a family of three) have access to free or subsidized high-quality preschool.

In other words, the families of nearly 10,000 young kids in Pima County have to pay roughly $10,000 to send a child to full-day, full-year preschool at a high-quality provider.

Other programs can cost less — an average of between $7,920 and $9,240, according to Pima County research, but is “good enough” good enough for your child?

The working group created the Pima County Preschool Investment Program, a framework that outlines the aim, the need, the benefits, the administration and the evaluation of a public preschool tuition subsidy plan.

They’ve been meeting with local officials and organizations to share PCPIP and solicit support.

Some of that support is financial, with more than $200,000 pledged by private donors, family foundations, the United Way of Tucson and Southern Arizona, the Southern Arizona Leadership Council and others.

PCPIP backers are hoping at least three of the five members of the Pima County Board of Supervisors will support the effort and supply funding — the figure of $4.8 million has been mentioned — to launch the program, with the hopes of expanding it.

There’s a problem, however. And it’s a lot more complicated and arcane than securing political support.

I spoke with County Administrator Chuck Huckelberry on Friday afternoon about PCPIP and funding prospects.

Public service announcement: We’re heading into technical tax and budgeting territory.

Huckelberry said that when PCPIP supporters first spoke with him, he thought maybe a preschool effort could be folded into the county library district, given the connections to literacy.

This would be good, because a levy could go on the county’s secondary property tax rate —which, in lay terms, has more capacity than the primary tax rate. But, the County Attorney’s Office said it would be too big a stretch.

Putting it on the primary tax rate would attract the ire of the Legislature, because primary taxes on owner-occupied residential property can never exceed 1 percent of the taxable value — anything more is paid by the state.

“Paid by the state” means dead on arrival.

So it’s possible the Board of Supervisors could make a stand for progress in Pima County and find a way to support PCPIP —it’s a proven investment that pays off.

Providing preschool should be a campaign issue to run on, not run away from. But, I’m not holding my breath.

This doesn’t mean the effort is doomed. Far from it.

I’ll get into why next week.

Sarah Garrecht Gassen is the Star’s Opinion editor. Email her at sgassen@tucson.com. This column is part of the Star Opinion project, “Growing Pima County: the Case for Early Childhood Education. “