Seven states had their waivers from No Child Left Behind renewed by the federal Department of Education Thursday, bringing the nationwide total to 42.

That more than 42 states need a waiver from No Child Left Behind shows how badly reform is needed. While waivers may be better than nothing, the waivers come with strings attached. States have to adopt education reforms preferred by Secretary of Education Arne Duncan. One requirement: The adoption of Common Core.

Without reform, the secretary of education essentially gets to bypass Congress and legislate education policy.

Fortunately, the Senate and House of Representatives have each passed their own replacements to No Child Left Behind. Both replacement bills would limit the federal role in education and give states more power. They would also prohibit the secretary of education from attaching conditions or incentives to any waivers from the law. "Our bipartisan bill that passed the Senate with 81 votes last week would end the need for waivers from No Child Left Behind and restore state and local control over the country's 100,000 public schools," said Senate education committee Chairman Lamar Alexander, R-Tenn., in a statement responding to the renewed waivers.

A conference committee to reconcile the two bills is expected to begin meeting in September.

Still, some say the language in the new bills might not put a stop to the secretary of education's method of legislating through waivers. "While the act would prohibit the Secretary from overtly specifying what he wants in state plans, it would let him keep vetoing plans until he gets what he wants," Neal McCluskey, the director of the libertarian Cato Institute's Center for Educational Freedom, wrote in a Daily Caller op-ed. "And it would be simple to communicate what those things are — wink, wink — in speeches, off-the-record conversations, etc." As a result, it may take even stricter language to keep the Secretary of Education from pressuring states into adopting education reforms.

Another obstacle for replacement is getting approval from the executive branch. The current scheme empowers the secretary of education over Congress, allowing the president to have an outsized influence over education laws. It could be difficult to get a president to approve changes to law that would take away his power, whether it's President Obama or his successor.

Duncan applauded the Senate reform bill when it passed with bipartisan support, but said it "still falls short." Two typical Obama allies were split on the bill, with civil rights groups opposed but teachers unions in support.

The White House issued a veto threat to the House version.

There's a thin line to thread on reforming No Child Left Behind. More than 42 states have shown why that reform is so badly needed.