When Donald Trump announced his candidacy in 2015, he ran through a litany of trigger issues for consumers of conservative media. Some have become increasingly inscrutable over time.

Like when he demanded an end to “Common Core.”

“Common Core should — it is a disaster,” Trump said during that speech. Former Florida governor Jeb Bush “is totally in favor of Common Core,” he said. “I don’t see how he can possibly get the nomination. He’s weak on immigration. He’s in favor of Common Core.”

Harsh words — apparently.

If you weren’t paying close attention to politics in about 2014, this phrase probably doesn’t mean much to you. “Common Core” is a shorthand for a set of educational standards adopted in most states that aimed to introduce more consistency over how and what students were taught. During President Barack Obama’s second term, with the standards being increasingly rolled out, parents became frustrated by changes to traditional problem-solving tools, leading to a backlash against the standards. That was amplified by conservative criticism that positioned Common Core as a top-down mandate from Washington that aimed to replace the role of parents with instructions from the federal government. (It wasn’t.)

So Trump, his thermometer on right-wing outrage as keenly tuned as always, used it to bash Bush and score points with conservative voters. Fox News and Fox Business mentioned Common Core more than 3,000 times between Jan. 1, 2013, and Jan. 1, 2017 — by which point criticism of the heavy-handed role of the federal government had become far less important to conservatives and Trump in particular.

But the outcry reinforced a particular bit of rhetoric: Parents know best and the government should not be in the business of mandating the teaching of unpopular or controversial things.

It’s a bit of rhetoric that has been revived with gusto of late as state governments and national conservative media personalities target “critical race theory.”

What is critical race theory? Well, if you’re not entirely sure, you join 4 in 5 other Americans who held that opinion in a poll reported by the Atlantic earlier this month. Despite that result, a majority of Republicans say that it should not be taught in schools.

That doesn’t answer the question, of course. In short, critical race theory holds at its center that racism is embedded in social and economic systems in the United States, often as a function of historical practices. While many Americans prefer to see racism as a function of bad, biased actors, critical race theory argues that racism is also systemic in ways that aren’t obvious.

It’s not clear that there are a lot of schools in the United States that are explicitly teaching critical race theory, though obviously the argument that there’s a systemic component to racism has been at the center of a lot of recent political debate. The Black Lives Matter movement is a prominent example, holding that law enforcement and the judicial system have ingrained racism that manifests, among other ways, in a disproportionate number of deaths of Black Americans at the hands of police.

But because there have been some efforts to develop curriculums that include components of critical race theory, such as the embrace of the New York Times’s 1619 Project, there has been a backlash that has centered on schools. The elevation of the issue in conservative media — as demonstrated in the graph above — has created an opportunity for right-wing and conservative politicians, including Trump. Various states have passed laws explicitly or indirectly targeting components of critical race theory in an effort by Republican elected officials to leverage that opposition.

Think about it: Not only does pushing back against critical race theory include the components of the Common Core fight that made it an important cause on the right seven years ago, but it also layers on top existing conservative frustrations about race and a healthy dose of hyper-patriotism.

We’ve known for a while that more-conservative Americans are also more likely to believe that White Americans face discrimination, even that Whites are more likely to face discrimination than non-White groups. This belief was common among Trump supporters in particular: A 2019 YouGov poll found that Trump supporters were more likely to say that White people face discrimination than that Black people do. So a formal educational curriculum that includes an emphasis on the role of anti-Black racism in American society would inevitably be particularly grating.

Then there’s the patriotism component.

The 1619 Project explored how the institution of slavery shaped the country. It became a lightning rod as academics took issue with some findings and, more broadly, as conservatives argued that it was fundamentally anti-American. That has become an incessant refrain: Evaluating the history of the United States in any way that isn’t centered on American greatness is unpatriotic.

So we get tweets like this, from Sen. Tom Cotton (R-Ark.), no stranger to understanding the value of elevating his profile by amplifying right-wing rhetoric.

The Atlantic’s Adam Harris gives the credit for critical race theory’s emergence as an incessant right-wing talking point to Christopher Rufo, a senior fellow at the conservative Manhattan Institute. Rufo has repeatedly drawn attention to the term, which has increasingly been used as an umbrella phrase that inaccurately includes any number of unrelated concepts and arguments.

Rufo sees that as advantageous, as Trump critic Charlie Sykes pointed out Monday. On Twitter, Rufo argued that the right had “frozen” perceptions of the term and was “steadily driving up negative perceptions.”

“We will eventually turn it toxic, as we put all of the various cultural insanities under that brand category,” he continued. “The goal is to have the public read something crazy in the newspaper and immediately think ‘critical race theory.’ We have decodified the term and will recodify it to annex the entire range of cultural constructions that are unpopular with Americans.”

In other words, Rufo argues for the value of detaching “critical race theory” from critical race theory and burdening it with various other ideas that are unpopular — precisely the criticism that many opponents make. Like “Common Core” before it, the phrase is now a container vessel, in this case for any claim that can be framed as race-centric or critical of America past or present, or that affects educational curriculums.

A poll commissioned by a group called Parents Defending Education shows how this works. It included questions such as one asking whether schools should “teach students that achieving racial justice and equality between racial groups requires discriminating against people based on their Whiteness.” Unsurprisingly, this highly negative framing (which probably derives from an entirely different source) was not received positively. But the poll was nonetheless elevated by right-wing commentators as evidence of the sort of hostility Rufo wanted to elevate.

It’s easy to understand why educational systems are particularly likely to yield an emotional response in parents. It’s not surprising that during Obama’s administration and now President Biden’s there has been a focus on some dire threat to education. Nor is it surprising that the current iteration — elevated by Trump as he sought reelection — has gained so much traction. But it’s also useful to consider critical race theory, like Common Core, for what it actually is and not for what it’s been attached to.