Rep. Bobby Scott is one of more than 80 members of the Congressional Tri-Caucus who say they won't vote for a revised No Child Left Behind unless it requires action at schools where one or more subgroups of students are failing to meet achievement targets. (Earl Gibson III/Getty Images)

From Rand Paul on the right to Elizabeth Warren on the left, members of the Senate education committee pushed aside their policy disagreements earlier this spring when they voted unanimously in favor of a bipartisan revision to the widely reviled No Child Left Behind law.

But key differences remain to be resolved in both chambers of Congress before the rebranded “Every Child Achieves Act” can make it into law. Among the stickiest: how and whether Congress should define which schools are failing to serve students well and need intervention.

It is an issue that has not only divided the parties but also pitted two traditional Democratic allies — civil rights groups and the National Education Association, the nation’s largest teachers union — against each other.

Now the Congressional Tri-Caucus has sided with dozens of civil rights groups and the Obama administration. In a letter to the Senate on Wednesday, more than 80 members of the Tri-Caucus said they cannot support the bill without key changes, including a requirement that states take action at schools that are failing to serve subgroups of children, such as those who are low-income, African American or English learners, or those who have disabilities.

Specifically, the Tri-Caucus — made up of the Congressional Black Caucus, the Congressional Hispanic Caucus and the Congressional Asian Pacific American Caucus — wants the federal government to compel states to act when a school fails to meet testing targets for subgroups of students two years in a row.

That type of change is anathema to many Republicans, who see it as a federal overreach, and to the NEA, which likens it to a return to the test-centric and overly punitive provisions of No Child Left Behind. But members of the Tri-Caucus say that the requirement is key to ensuring that states do not overlook the nation’s neediest children.

Rep. Robert C. “Bobby” Scott (Va.), the ranking Democrat of the House education committee, said he and his colleagues are seeking a new law that “honors the civil rights legacy of the law and fulfills the needs of all of America’s children.”

The 2002 No Child Left Behind law was so unpopular in part because of its rigid definition of a “failing” school — any school in which one subgroup of students, such as African American children or those with disabilities, failed to meet test score targets set by the federal government. Schools that were generally doing well but where one group of children missed test score targets by a few points were lumped together with truly broken schools that failed year after year to educate their students.

The Senate’s bipartisan revision of the law has swung in the other direction, giving states latitude to decide how to judge schools’ success, including how much standardized test scores should count. States are also responsible for deciding which schools don’t measure up and what to do to improve them.

Civil rights groups fear that turning over all that control to states opens up the possibility that they will hide the poor achievement of disadvantaged children.

Adding the amendment that the Tri-Caucus and civil rights groups favor would not re-create No Child Left Behind because the federal government doesn’t define the testing targets or the interventions, said Kati Haycock, president of the Education Trust. Schools wouldn’t be required to fire principals or teachers but would have latitude to address their specific problems in ways that make sense locally, she said.

“What we’re trying to do is thread the needle, saying you’ve got to take this seriously, you can’t year after year miseducate one group of your kids — you need to do something. But we’re not going to tell you how to do it.”

Several key business groups, including the U.S. Chamber of Commerce, also favor such a provision.

The NEA opposed a similar amendment when it came before the Senate education committee, arguing that it would continue to overemphasize standardized testing and again cause many schools to be wrongly labeled as failing. In a letter to the Senate in April, Mary Kusler, NEA’s director of government relations, called it “reminiscent of the Adequate Yearly Progress system,” invoking what has become perhaps the best-known and most hated part of No Child Left Behind.

“The bill the Senate approved is headed in the right direction because it represents a strong bipartisan effort to improve upon the failed test, label, and punish policies of No Child Left Behind,” NEA President Lily Eskelsen García said in a statement.

“As we move forward, we will continue to urge Congress to go even further in helping each and every student, particularly those living in poverty and with the greatest educational needs. We still have work to do to ensure equity and opportunity for all students. We still need to ensure the system looks at more than test scores. We need a system that takes a holistic approach of focusing on the whole child.”

The union supports the civil rights coalition’s push to require action at the bottom 5 percent of schools in each state and at high schools with low graduation rates.

The civil rights coalition includes more than 40 organizations, including the NAACP, National Council of La Raza, the National Urban League and other such influential groups. But the civil rights community is not unanimous. Groups such as the Advancement Project and the Schott Foundation for Public Education have not signed on to the coalition, saying that its faith in test-based accountability is misplaced and does nothing to ensure that all children have access to rich learning opportunities and resources.

It’s unclear how the competing priorities on school accountability will shake out when Every Child Achieves heads to the Senate floor in the next several weeks. Some Democrats are caught between two constituencies with very different views on a key issue. But key Democrats, including Sen. Patty Murray (Wash.), the ranking Democrat of the Senate education committee, have signaled that they want to see the current bill amended to strengthen the federal government’s role in holding schools accountable for teaching all students.

“While Senator Murray sees the federal guardrails she was able to get included in the Every Child Achieves Act as positive steps, she also believes Congress should continue working to strengthen accountability systems under the bill as it moves to the Senate floor and in conference,” a Murray aide said, “including stronger protections from the federal level to identify struggling schools and help them get the supports, resources and locally designed interventions they need to serve all of their students.”

Meanwhile, many of the Republicans who dominate both chambers are loathe to give Washington any say in school accountability.

Sen. Lamar Alexander (R-Tenn.), who chairs the Senate education panel and worked with Murray to hammer out the bipartisan Every Child Achieves bill under consideration, has been one of the strongest voices in favor of reducing the federal role in education, including in school accountability.

“Our bill’s proposal to continue the law’s important measurements of academic progress of students in all groups — but restore to states, school districts, classroom teachers and parents the responsibility for deciding what to do about improving student achievement — is the best way to achieve higher standards, better teaching and real accountability,” Alexander said in a statement. “As a result of this consensus, our bill has attracted the support of governors, chief state school officers, school superintendents, and teachers’ organizations.”