Senate Health, Education, Labor and Pensions Committee Chairman Sen. Lamar Alexander (R-Tenn.) listens to testimony about No Child Left Behind on Jan. 21. (Susan Walsh/AP)

As Congress undertakes its most serious effort to rewrite the No Child Left Behind education law, backlash against standardized testing has prompted vigorous debate about whether the federal government should continue requiring annual exams.

Sen. Lamar Alexander (R-Tenn.) has written a draft revision that proposes two options:

●Continue requiring annual tests every year in third through eighth grades and once in high school, the policy favored by the Obama administration and a group of the nation’s most influential civil rights groups.

●Or get rid of those annual tests and give states much more room to develop their own testing regimes. One option for states would be to require assessments once each at the elementary, middle and high school levels. That is known as “grade span testing,” an approach that is favored by the National Education Association, which is the nation’s largest teachers union, and by many parents and teachers who say overtesting has warped schools.

Now, trying to bridge the gap between those two sides, is the American Federation of Teachers, the nation’s second-largest teachers union, and the Center for American Progress, a liberal think tank with ties to the Obama administration.

The two groups want to keep administering tests each year and keep publishing data that show — for each school, school district and state — how subgroups of students are faring.

But most of those tests wouldn’t be used to judge schools. Only once at each grade span would the tests actually “count,” i.e., be part of an accountability system used to identify and force change at struggling schools.

Under No Child Left Behind, every annual test has counted, and schools that have persistently failed to meet achievement targets have been subjected to a range of sanctions and interventions.

Alexander, chairman of the Senate Committee on Health, Education, Labor and Pensions, and Sen. Patty Murray (D-Wash.), the committee’s ranking member, aren’t saying what they think of the hybrid approach.

“When our hearings are completed, I will work with Sen. Murray and others to see what the best ideas are,” Alexander said through a spokeswoman. A spokeswoman for Murray reiterated the Democrat’s oft-stated concern “about anything that would roll back the annual statewide assessments.”

The union and the think tank argue that their proposal is a way to thread the needle on a difficult issue. Achievement gaps would still be plainly transparent, they argue, but schools, teachers and students could ratchet down the stress and time they expend on testing in favor of more time and energy for teaching and learning.

“After a decade of No Child Left Behind and Race to the Top, we know that an environment with high-stakes, annual tests forces schools to focus on compliance, not on kids,” AFT President Randi Weingarten said in a statement. “Ultimately, this re-envisioned accountability system, with grade-span testing as one of many measures, will allow us to put kids, not high-stakes tests, at the center of everything we do.”

A spokeswoman for Education Secretary Arne Duncan, who has pressed for annual testing, declined to comment on the AFT-CAP proposal. But the proposal has drawn criticism from champions of the Obama administration’s approach to testing.

“Dumb Policy Ideas Not Limited to the Far Right,” reads the headline of a blog post by Kati Haycock, president of the Education Trust, a nonprofit that joined more than a dozen civil rights groups in arguing that annual testing is necessary to shine a light on achievement gaps that leave too many poor and minority children lagging behind their peers.

Haycock and other critics argue that the proposal would allow schools to slide by without being held accountable for their students’ learning and would make it difficult to recruit teachers for tested grade levels because there would be so much pressure on them to get good test scores for the whole school.

“In some ways, we’re not getting rid of all stakes, we’re just making some tests count much, much more than others,” said Anne Hyslop, a senior policy analyst for Bellwether Education Partners, who says the proposal would create new problems.

Hyslop said the proposal would also make it more difficult to overcome one of the key weaknesses of No Child Left Behind: its focus on proficiency rates in math and language arts.

Many experts argue that proficiency rates are more reflective of students’ income levels than of their schools’ success and that it would be fairer and more accurate to judge schools by how much progress their students make annually. That would be difficult if not impossible to do if tests count only once per grade level, Hyslop said.