LOS ANGELES – If Congress fails to approve changes to a key school accountability bill, federal officials will consider waiving some mandates for states that agree to educational reforms.

Federal education officials said they would prefer that Congress approve a substantially revised version of No Child Left Behind, a package of mainly testing reforms that was the Bush administration’s signature education law, approved in 2001. President Obama has asked Congress to reauthorize the bill by this fall. But lawmakers may miss that deadline, Education Department officials said.

If an agreement cannot be reached, Education Secretary Arne Duncan said, his department is prepared to offer states that undertake reform efforts some flexibility on federal requirements. “The worst-case scenario is Congress does nothing and we do nothing,” Duncan said last week.

Rep. George Miller, D-Calif., who heads the education and workforce committee, said he hopes that Congress will take action this legislative session.

“It’s a moral imperative, an economic necessity and simply the right thing to do for our children,” he said in a statement.

Duncan did not offer specifics on potential reforms. But he said he was interested in an increased emphasis on student improvement on standardized test scores, among other things.