The answer, quite simply, is immigration reform and Common Core. But on immigration, Jeb’s position is little different from that of other leading GOP contenders, including Marco Rubio and Scott Walker .

On June 15, Jeb Bush is expected to announce his bid for the presidency. In many ways, he is an attractive candidate. He possesses universal name recognition, ready access to funding, an Hispanic spouse, and (unlike his presumed opponent) a scandal-free record of public service. He is also relatively young, undeniably bright, and conservative on most issues. So why the strong opposition by so many conservatives?

Common Core is another matter. More than any other issue, Jeb Bush has made Common Core his own, and he has been unwilling to shift that position. One can admire his principled stand, but on this issue he is wrong, and wrong to an extent that may deny him the nomination.

Common Core would impose a national standard for basic subjects taught in public schools across the land. To achieve this standard would require standardized testing and a school year focused on “teaching to the test.” Doing so would deny teachers the opportunity to teach other, more valuable lessons.

I recall my fourth-grade teacher – our beloved Miss Jones – who spent one full hour every day reading from classic works of literature suitable to our grade level. Over the course of the year we experienced A Tale of Two Cities, The Prince and the Pauper, Tom Sawyer, and a half-dozen other memorable tales. The educational value of this exercise was immense, but I doubt it would survive in a curriculum focused on Common Core. It probably doesn’t survive very many places as it is.

As many critics recognize, Common Core would be the death knell for whatever is fresh, and different, and human and inspiring in the curriculum. Local school boards and administrators, and individual teachers, need to have the right to decide, not a distant bureaucracy imposing a standardized level of achievement.

Not that I am opposed to achievement. Miss Jones held us to standards that would be the envy of Common Core classrooms today. By the time we finished the Dickens classic, we knew as much about French history, European politics, and the operation of the guillotine as any fourth-graders in the nation. We had also acquired a larger vocabulary and a finer appreciation for the nuances of English prose.

Miss Jones did very little testing. She didn’t have to, because during the hours we spent with the classics, she had our full attention. Our eyes were opened to the humanity of Twain and Dickens, but also to that of Miss Jones. Those who support national standards do not seem to appreciate this point. Which is to say, they do not understand teaching.

Robert Frost, the great poet who spent many years teaching at prestigious universities, once said he could assign grades based on the “gleam in a student’s eye.” That is probably not an approved method of evaluation at most schools, but it makes an important point. The basis of all true teaching is the human exchange between teacher and student. Nothing of value gets taught in a classroom in which humanity has been stamped out. And teaching to the test is about as inhuman as it gets.

Common Core is by definition opposed to this kind of humanity. When the priority becomes raising average test scores, individual needs are lost sight of. Both high achievers and low achievers are poorly served as resources are focused on raising the average classroom scores, but it is especially the high achievers who suffer. The message to these students, those who have the greatest potential to make important contributions to society, is “pass the test and you’re done.” That should never be the message of teachers or schools. The classroom should demand the most from students, not the minimum. Students should be challenged and inspired, not told that their task is to pass a standardized test written by Washington officials.

Common Core also fails because it imposes national standards over state and local priorities. It is unlikely that students from west Texas will have the same background or interests as students from Manhattan or south Florida. It is likely that the literary tastes of students from Vermont differ from those of students from Oklahoma. Students should not be made to study the same material or to arrive at the same conclusions. But under Common Core, the local culture that determines so much of how one thinks must be suppressed. The standardized material censors out all local “bias,” except of course the politically correct bias of liberals in Washington.

One of the most insidious aspects of Common Core is the potential for federal officials to impose not just neutral standards, but ideologically biased content in the name of testing. When nearly every question in the reading section hinges on race, class, and gender, schools are forced to inculcate a leftist ideology. When science questions focus on climate change and social science stresses income equality, schools move farther to the left.

Even by its own minimal standards, Common Core fails, because it generates resistance on the part of students and teachers. Even if one discounts the effect on high achievers and the ideological bias of Common Core, its effectiveness in reaching the goal of basic competency must be questioned. Once students are led to believe that the purpose of education is to pass a test of any kind, respect for learning has been compromised. Miss Jones understood this truth about education. I fear that Gov. Bush does not.

Those who support Common Core are taking public education in the wrong direction. Testing will always be a part of education, but testing should not be standardized out of Washington, nor should it be anything but a minor part of the classroom experience.

It is not too late for Gov. Bush to abandon his support for Common Core. As a two-term governor of Florida, he managed the state well. He lowered taxes every year he was in office. He eliminated the state’s onerous intangible property tax. His business-friendly policies spurred employment and living standards. And he raised educational standards without the imposition of standards devised in Washington.

Bush has said that he intends to “run on his record.” If he does, it will be clear that in most respects he is a committed conservative. On immigration, he needs to repeat “close the border” a thousand times and leave it at that. On Common Core, he should drop the subject altogether.

Common Core is a litmus test for conservatives because it touches the true third rail of conservative politics: the overriding importance of individual liberty. The federal government has no right to step into the classroom and dictate what and how children should learn. Jeb Bush is an attractive candidate in many respects, but he will never gain the support of conservatives until he abandons his quixotic support for Common Core.

Dr. Jeffrey Folks is the author of many books on American politics and culture, including Heartland of the Imagination (2011). For more than three decades, he taught at the college level.