In January, he sent an email to supporters with the subject line "Rotten to the Core," according to Bloomberg. In that email, he called out the Common Core as containing "anti-American propaganda, revisionist history that ignores the faith of our Founders and data-tracking of students from kindergarten on."
It's not entirely clear what Paul means here, as the Common Core only includes standards for reading and math, not history.
Paul also takes aim at the Common Core for the oversized role he perceives the federal government is taking in education. "I don't think there's really a constitutional role for the federal government in education. So I'm not for a national curriculum," Paul said in an interview with Breitbart News in October.
To be clear, the Common Core State Standards are actually not a national curriculum. Rather, they're a set of standards developed by state leaders and private Washington groups to improve learning outcomes of students across the US. This nuance means that states have control over the rollout the standards and how lessons will be taught to ensure students grasp the key concepts.
The Common Core was also adopted by states, rather than mandated by the federal government, though they were certainly backed and incentivized by the Obama administration.
Paul is clearly setting himself apart from another potential GOP nominee who supports the Common Core - former Florida governor Jeb Bush, a major education reformer.
"If there's a Republican candidate out there - let's just say there's a hypothetical one that's for Common Core. I'm saying that that hypothetical candidate that's for Common Core probably doesn't have much chance of winning in a Republican primary," Paul said in an interview in October at a political event.
Paul's arguments are likely to emerge when No Child Left Behind reauthorization begins as he's the chairman of the Senate subcommittee on K-12 education.
We reached out to Paul and will update this post if we hear back.