Amanda Paulson

A new coalition of Common Core supporters, this time from the higher-education community, announced itself. Its mission: to raise awareness about the importance of the standards and try to counter the spread of misinformation and the growing backlash against the standards.

It's a battle that has become central in the education world lately, and is spilling out into more general debate, as Common Core becomes a key issue in many midterm campaigns.

Recently, South Carolina and Oklahoma have joined Indiana in dropping the standards, bringing the number of states with Common Core down to 43.

Tea Party candidates and many Republicans have started using opposition to Common Core as a sort of litmus test, with many referring to it as "ObamaCore."

On the left, a growing number of educators have raised concerns over the standards for early-elementary grades, and have pushed for a slow-down on Common Core implementation and high-stakes accountability.

And a number of states have announced they no longer plan to use one of the two big assessments being developed to align with Common Core.