WASHINGTON -- A hearing Tuesday exposed varied criticisms of the tightrope act on the federal role in local schools in a bipartisan rewrite of the controversial No Child Left Behind law expected to hit the Senate floor in the coming weeks.

Senators and witnesses agreed the original law is flawed by a too-rigid approach to student assessment, unattainable standards and over-reliance on standardized tests. It has proved incredibly unpopular with educators, and dozens of states -- including Georgia -- have sought No Child Left Behind waivers offered by the Obama administration.

The administration also is pushing for a new law from Congress to replace the one signed in 2001 by President George W. Bush.

The 868-page bill, co-written by Iowa Democrat Tom Harkin and Wyoming Republican Mike Enzi, delegates more authority to states and changes test-based proficiency measures into broader aims of college- and career-readiness.

But even the authors expressed unease with the new bill, as Enzi would have liked less of a federal role and Harkin wanted a stronger one.

“This bill is not Mr. Enzi’s bill, and it ain’t mine, either, but it is ours,” Harkin said.

They heard from a panel of 10 teachers, administrators and experts, who had varying quibbles with the current law and its potential successor.

"As an educator, just the connotation of the term No Child Left Behind, it really is demoralizing to us at this point because there is so much focus on testing, testing, testing that we have no time to teach, and it really has become that way in the schools," said Pam Geisselhardt, a coordinator of gifted and talented students in Columbia, Ky.

The proposed rewrite, which is four years overdue, ends the "adequate yearly progress" standards of NCLB and instead has states assess "continuous improvement." The bill provides federal money to schools with the lowest achievement levels, highest dropout rates and largest racial achievement gaps. It also mandates that school districts devise teacher evaluation programs.

Wade Henderson, president of the Leadership Conference on Civil and Human Rights, argued that this approach did not go far enough to set achievement standards for the most vulnerable students -- as it focuses federal resources only on the worst 5 percent of schools in each state in performance and achievement gap.

Henderson said the gospel of "flexibility" should not bring about "the end of national standards that have been arguably the most significant driver of the improvement of public schools that we’ve seen over the last decade of No Child Left Behind."

Henderson brought a letter signed by 28 civil rights and education advocacy groups, including the NAACP, the American Civil Liberties Union and the Education Trust, saying the groups could not support the law in its current form.

The letter also was signed by the U.S. Chamber of Commerce, the powerful conservative business lobby. Margaret Spellings, who helped craft the original No Child Left Behind law in the Bush White House, now is a senior adviser at the chamber.

Others on the panel argued the bill constitutes too much federal meddling in state and local affairs. Idaho Superintendent of Instruction Tom Luna touted his own state's efforts to institute merit pay for teachers.

"I don’t see necessarily a problem with the federal government requiring it, but I think it goes too far if the federal government tries to define it or regulate it," he said.

The bill passed out of the Health, Education Labor and Pensions Committee last month and will take weeks to get to the floor, where its prospects are perilous at best.

Sen. Johnny Isakson, R-Ga., focused his questions Tuesday on flexibility for special needs children, who he said should be evaluated based on individual education plans rather than a blanket standard. He voted against the bill in committee.

"There are a number of things that need to be done and improved and I hope we can get them done," Isakson said.