There might have been a lot of bipartisan love when the Senate education committee considered—and unanimously passed—a bill to rewrite the No Child Left Behind Act. But there were a number of key issues lurking below the surface of all that good feeling, including the question of whether or not states should have to identify a particular percentage of low-performing schools for interventions.

That’s something the Obama administration would really like to see, U.S. Secretary of Education Arne Duncan noted in his initial statement congratulating committee members for crafting a bipartisan bill. And it’s something that some folks on the committee, including Sen. Michael Bennet, D-Colo., would also favor. In fact, Bennet introduced an amendment during consideration that would add the 5 percent requirement to the bill. But then he withdrew it, saying lawmakers could work on the issue as the legislation moves through the process.

Here’s the thing: The five percent requirement is already being tested at the state level, right now, through the Obama administration’s waivers. States have to identify 5 percent of their lowest performing schools for major interventions. But that hasn’t always gone super smoothly.

In fact, one of the key issues that’s come up, again and again in state waiver renewal applications, is just when a school should get out of “priority” status. In some states, including New Mexico, which already got its waiver application approved, low-performing schools are making progress—but they aren’t moving the needle on student achievement fast enough to meet the strict “exit criteria” that the state initially proposed. The problem? States may have other schools that are have greater academic need—and only so many resources to devote to turnarounds. More in this story.

On the other hand, of course, the current Senate bill directs some resources to turnarounds but doesn’t specify a particular number or percentage of schools for dramatic interventions. So states, or districts, could, conceivably, decide not to intervene in some pretty needy schools, or provide them with more targeted help.

So does having a bottom five percent make sense? Or not? Comments section is open.