Jeb Bush’s early entry into the 2016 presidential campaign has already turned the Obama administration’s Common Core education standards into one of the hottest topics among conservatives ahead of the 2016 primary.

Bush, who had left office as Florida’s governor by the time the standards were unveiled, doggedly supported them, both in his personal statements and through his nonprofit Foundation for Excellence in Education. The standards were and are controversial, facing ferocious opposition both from Tea Party conservatives and teachers unions. The most dramatic political manifestation of the anti-Common Core movement occurred in the 2012 election in Indiana, where conservative activists helped install a liberal, union-backed opponent of Common Core as state educational superintendent, defeating an incumbent Republican who supported the standards.