In just five months, the Obama administration has freed schools in more than half the nation from central provisions of the No Child Left Behind education law, raising the question of whether the decade-old federal program has been essentially nullified.

On Friday, the Department of Education plans to announce that it has granted waivers releasing two more states, Washington and Wisconsin, from some of the most onerous conditions of the signature Bush-era legislation. With this latest round, 26 states are now relieved from meeting the lofty — and controversial — goal of making all students proficient in reading and mathematics by 2014. Additional waivers are pending in 10 states and the District of Columbia.

“The more waivers there are, the less there really is a law, right?” said Andy Porter, dean of the University of Pennsylvania’s Graduate School of Education.

While No Child Left Behind has been praised for forcing schools to become more accountable for the education of poor and minority children, it has been derided for what some regard as an obsessive focus on test results, which has led to some notorious cheating scandals. Critics have also faulted the law’s system of rating schools, which they say labeled so many of them low performing that it rendered the judgment meaningless.