There was plenty of talk. Senator Sanders admitted he was “sick and tired of hearing” about Secretary Clinton’s emails. Senator Webb jabbed Wall Street. Governor O’Malley championed the middle class. And Governor Chafee was also there. But nobody said anything about K-12 education. Why not?

There was some talk about higher education. Both Senator Sanders and Secretary Clinton insisted we need some way to relieve student debt loads, maybe with free college tuition. Governor O’Malley bragged about low tuition rates in his state.

But only Secretary Clinton mentioned early childhood education, saying offhand that every child needed it to live up to his or her “God-given potential.”

Seems odd. The Democratic Party, after all, is the party of both Head Start and Race To The Top. The Democrats’ Big Tent includes both “Test-Em-n-See” Arne Duncan and Curmudgucrat Peter Greene.

It seems in the high-stakes world of primary debates, these stark differences between leading Democratic voices would offer a chance for some lively back-and-forth on key issues. What should we do with the Common Core? How should teachers be evaluated? How do we know if a school is doing a good job?

We didn’t hear it.

Loudmouth education parvenu Campbell Brown calls it a conspiracy. The Democratic Party, she claims, is in the back pocket of the teachers’ unions. They don’t even dare RSVP to her debate invitation.

Peter Greene thinks the answer is even simpler: “when it comes to public education in this country, none of the candidates actually gives a shit.”

In The Atlantic, David Graham thought there was just nothing much to disagree about. “Overall,” Graham opined, “the Democratic candidates simply don’t have the same divisions that the Republicans one [sic] do.”

But none of those explanations makes sense. This sort of forum offers candidates a chance to grab attention. Clinton’s identification with the Obama administration makes her an easy target. Yet none of them took it.

Here in the Great State of New York, we’ve seen how protest candidates can and do win votes by blasting other Democrats. I’m stumped why none of these candidates—not even the fire-breathing Senator Sanders—took this opportunity to do so.

Here’s my hunch: In the fervent calculations of any serious presidential campaign, candidates must make careful bets about issues and positions. In the face of Mr. Greene’s assertion that the candidates don’t care, I think candidates will care about what they think voters will care about.

Why didn’t candidates make political hay about K-12 education? Because they thought it would not win them any votes. With their finely tuned political antennae, these leading candidates concluded that Democrats in general did not want to hear about it.

Compare that to the GOP, where every candidate is forced to pay lip service to creationism. Compare that to the GOP, where every candidate falls all over him- or herself to show off his or her penchant for “education reform.”

Leading Democrats, in contrast, don’t air their differences in public. Why not? I’m no cynic, but it seems obvious to me that all candidates have agreed implicitly that their differences will not give them a competitive advantage. In short, none of them is willing to bank on a groundswell of support for iconoclastic progressive educational notions.