-- The number of schools labeled as "failing" under the nation's No Child Left Behind Act could skyrocket dramatically this year, Education Secretary Arne Duncan said Wednesday.

The Department of Education estimates the percentage of schools not meeting yearly targets for their students' proficiency in in math and reading could jump from 37 to 82 percent as states raise standards in attempts to satisfy the law's mandates.

The 2002 law requires states to set targets aimed at having all students proficient in math and reading by 2014, a standard now viewed as wildly unrealistic.

"No Child Left Behind is broken and we need to fix it now," Duncan said in a statement. "This law has created a thousand ways for schools to fail and very few ways to help them succeed."

Duncan presented the figures at a House education and work force committee hearing, in urging lawmakers to rewrite the Bush-era act. Both Republicans and Democrats agree the law needs to be reformed, though they disagree on issues revolving around the federal role of education and how to turn around failing schools.

A surge in schools not meeting annual growth targets could have various implications. The most severe consequences - interventions that could include closure or replacing staff - would be reserved for those schools where students have been failing to improve for several consecutive years.

Duncan said the law has done well in shining a light on achievement gaps among minority and low-income students, as well as those who are still learning English or have disabilities. But he said the law is loose on goals and narrow on how schools achieve them.

"We should get out of the business of labeling schools as failures and create a new law that is fair and flexible, and focused on the schools and students most at risk," Duncan said.

Russ Whitehurst, director of the Brown Center on Education Policy at the Brookings Institute, said some states and districts have dug themselves into a hole by expected greater gains in the final years.

"The reality is coming home that you can't essentially demonstrate very little progress for ten years and then expect all of your progress to occur in the last two or three years," Whitehurst said.

He said some states believed improvement would accelerate as students advanced, creating a "snowball effect," while others put off the heavy lifting to avoid the consequences.

Daria Hall, Education Trust's K-12 policy director, said it was also important to distinguish between schools that don't meet the annual growth benchmark for one year, versus those who have failed to do so for two consecutive years and are labeled as being "in need of improvement."