For almost two decades now, the U.S. has been working to improve its schools by holding them accountable for results on standardized tests. And there's been some success, with America's lowest performing students showing marked gains.

Unfortunately, similar progress hasn't been made for students in the middle or at the top. That shouldn't be surprising, since the standards, and especially the tests, that most states put into place - including in Idaho -were set at ridiculously low levels. The federal No Child Left Behind act, in fact, encouraged this behavior by demanding that states aim to get 100 percent of their students to the "proficient" level by 2014 - but let the states define proficiency.

Now we see the result of these short-sighted policies: Many young people have been taking and passing these tests, yet still emerge from high school unready for college-level work in the core subjects, and unready for decent paying jobs. As a result, many were sent to "remediation" and so taxpayers paid twice to educate them. (According to a recent study, Idahoans could have saved some $12 million in 2007-08 on such remediation.)

The Thomas B. Fordham Institute -the conservative think tank where we examine policy issues and promote reforms in K-12 education - reviewed Idaho's standards and graded them a C in English language arts and a B in mathematics. In 2010, however, Idaho adopted the Common Core State Standards, the product of a multi-year state-led effort aimed at aligning school expectations with the demands of the real world (both college and modern jobs). We rated these standards a B+ in English language arts and an A- in math. Idaho also set the bar quite low in the past by declaring many students at a "proficient" level who we really know to be performing at just a basic level on core English and mathematics skills.

We have long advocated for higher, clearer school standards that focus on essential skills and vital knowledge so as to prepare students to be productive, self-sufficient citizens. We also believe that key education decisions belong with states, communities, teachers and parents and were therefore glad that the Common Core limited its work to standards and did not push into curriculum. To be clear, our support for the Common Core stems from the standards' quality and little else. We have been, for example, far less supportive of a similar multi-state effort around science standards because we fear the final product is less worthy of adoption.

In recent months, we have been puzzled by the small but vocal minority of conservatives who have joined forces with some on the far-left to oppose the Common Core. It's appropriate, of course, to worry about threats like federal intervention into schools, ideological indoctrination of students, and poor-quality instruction. But the Common Core doesn't promote any of those things. Instead, it pushes schools, teachers and students to higher levels of achievement and deeper levels of skill-and-content knowledge than most have accomplished in the past - and more than Idaho's old standards even aspired to.

Leaders in Idaho were elected by the people to ensure that the billions of taxpayer dollars spent on public education are used effectively and efficiently to educate our next generation. These officials should now stand up to misguided and ill-informed political attacks and demand answers from both liberal and conservative critics of the Common Core: would those on the left really remove testing and other measures that ensure that parents and teachers know whether students are learning all that they should - and how to help those who aren't? Would those on the right really have Idahoans send their children to schools that are forced to scrap the standards they have spent time and money implementing and return to tests that are worse?

We welcome debate over the Common Core but the facts are clear: Idaho, to its credit, has opted to strengthen its standards for student learning. Opponents have an obligation to say what they would do instead. Settle for yesterday's weak standards and today's lackluster performance? If someone offers a better option, we will support it. If states choose to use flexibility built into the Common Core to improve their standards even more, as Governor Walker seems to have suggested, we will support that, too.

In the meantime, however, something very promising is on the table. Attention and energy should go into devising the best way to put it into practice in Idaho and to ensure that future tests report accurately on how students and schools are doing in relation to these ambitious standards. Idaho made a choice for the better when it adopted the Common Core. It should not turn back now, especially under pressure from a few loud opponents without a better plan.

Michael J. Petrilli and Michael Brickman are, respectively, executive vice president and national policy director of the Thomas B. Fordham Institute, a right-of-center education policy think tank. Petrilli served in the George W. Bush administration and is also affiliated with the Hoover Institution while Brickman served as education policy advisor to Wisconsin Gov. Scott Walker.