I think the whole idea of federalizing lower education was a major error. From How the Common Core Went Wrong:
Critics have tagged the Common Core with the pejorative "ObamaCore." The gibe is more instructive than many realize. The Affordable Care Act and the Common Core both involve ambitious efforts to change whole swaths of American life, though the practical impact of each was intentionally shrouded in uncertainty. Both would have benefited from more scrutiny early on but are now increasingly entrenched. In health care, critics have found it a losing strategy to talk about simply repealing the ACA without talking about what should replace it. They need to offer plausible alternatives to have a shot at policy or political success. Meanwhile, the ACA has started to change American medicine. The same is true of the Common Core. Five years on, it has started to change instruction, textbooks, and curriculum.