The Senate voted 81-17 to overhaul the Bush-era No Child Left Behind Act Thursday afternoon, passing a bipartisan bill that gives states more flexibility to hold schools accountable for students' test scores.

Everyone wants to fix No Child Left Behind, said Sen. Lamar Alexander (R-Tenn) after the vote was counted. Thats the consensus we began with.

The overwhelming vote passed the Every Child Achieves Act, a bipartisan proposal sponsored by Alexander and Sen. Patty Murray (D-Wash). The bill keeps in place current federal testing requirements but gives states more freedom to determine how to hold schools and teachers accountable for students' test scores. The current testing schedule mandates that schools test children in reading and mathematics every year in grades three through eight and again once between grades nine through 12.

The House of Representatives passed its own version of a NCLB overhaul last week called the Student Success Act.

This is a complicated piece of legislation, Alexander said. There are crocodiles in every corner. The fact that it passed with a wide margin despite these complexities, he said, is remarkable.

I am so proud that our bill is a strong step in the right direction to finally fix NCLB, Murray said. It was a compromise, she added: It wasnt the bill I would have written on my own.

However, the bills next steps are unclear, since even its supporters concede President Barack Obama is unlikely to sign it in its current form.

I commend the hard work of Senator Alexander, Senator Murray, and their colleagues to get us this far, U.S. Secretary of Education Arne Duncan said in a statement. However, this bill still falls short of truly giving every child a fair shot at success by failing to ensure that parents and children can count on local leaders to take action when students are struggling to learn. Duncans thoughts echo those of several civil rights groups that oppose the bill because they say its accountability measures don't go far enough. The bill would also need to be reconciled with the NCLB overhaul the House passed, which Obama has suggested he would veto.

Former President George W. Bush signed No Child Left Behind in a moment of bipartisanship following September 11, 2001. The law made federal funding of education conditional for the first time, tying it to student achievements on regular standardized tests. It set the goal of total proficiency in reading and math by 2014 -- a goal that has yet to be reached, and that many have since described as utopian.

Because NCLB required reporting of how different socioeconomic and ethnic groups fare on standardized tests, it has been credited with exposing the so-called achievement gap between black and white students. Scholars have also credited the laws accountability measures with an overall rise in student achievement. But as soon as it was implemented, the law has been much maligned, even by its initial supporters. Teachers and their allies have criticized the law for using too blunt a tool -- raw standardized test scores -- to measure school success. The tutors that the law requires underperforming schools to pay for have proven to be largely ineffective. And some have blamed the law for a declining focus on studies outside of math and reading, such as social studies and the arts.

When Barack Obama first ran for president, he promised to replace NCLB. Once in office, he gave Congress a deadline of 2011 to renew the law, which both the Senate and House failed to do. The workaround Obama and Duncan came up with lets states apply for waivers that would release them from the laws toughest penalties in exchange for agreeing to certain Obama-preferred reforms, such as including student test scores in teacher evaluations. Now, most states operate under NCLB waivers. In 2013, Congress once again attempted an overhaul; the House passed a Democrat-supported bill , but the Senate stalled after marking up a corresponding bill in committee.

While groups across the political spectrum are eager to replace the outdated NCLB, the Every Child Achieves Act has received its fair share of criticism from both the left and the right. Civil rights groups complain that the bill does not contain enough accountability measures to ensure that states will attempt to rectify achievement gaps between groups of students. Meanwhile, conservatives lament that the bill does not do enough to reduce the role of the federal government in education.

The principle of accountability is not negotiable to us... educational systems must be held responsible for narrowing and eliminating gaps in achievement, said Leslie Proll, director of the NAACP Legal Defense Funds Washington, D.C. office, on a call with reporters Thursday morning. Proll was joined on the call by other civil rights advocates.

Both national teachers' unions expressed tempered support for the bill. "The Every Child Achieves Act, which passed the Senate today, represents a fundamental and positive change of direction for public education, said Randi Weingarten, president of the American Federation of Teachers. More must be done to address the needs of historically disadvantaged children, but this bill offers a significant piece of the puzzle.

The National Education Association's Lily Eskelsen Garcia was more jubilant. Every student in America will be better off under this legislation than the generation of students wronged by No Child Left Untested, she said. This bill reflects a paradigm shift away from the one-size-fits-all assessments that educators know hurt students, diminish learning, and narrow the curriculum and that they fought to change. Now, Congress must act swiftly to reconcile the House and Senate legislation and get a bill to the Presidents desk.