California Gov. Jerry Brown, shown Sept. 16, said that “a test based on a different curriculum does not make a lot of sense.” (Justin Sullivan/Getty Images)

California is on a collision course with the U.S. Department of Education over its plans to suspend standardized tests this school year – a move that Education Secretary Arne Duncan says is wrong-headed.

Concerned that other states might follow suit and in an attempt to shut down California’s rebellion, Duncan is threatening to withhold a small portion of the $1.4 billion California receives annually from Washington to help educate poor students in the country’s most populous state.

Like 44 other states and the District of Columbia, California has adopted the new Common Core academic standards in math and reading, and its teachers are using new curricula and materials for grades K-12 this school year.

Federal law requires states to test students in math and reading in grades 3 through 8 and once in high school. That requirement, a cornerstone of the 2002 No Child Left Behind law, is designed to allow parents, regulators and the public to track student performance and hold schools accountable.

But exams based on the new Common Core standards are still being crafted and won’t be ready until next school year, leaving states in a quandary: If they are teaching new material, and new tests aren’t ready, do they use the old tests?

California lawmakers said no, and voted Sept. 10 to end funding for standardized testing for at least this school year. Instead, students can take practice versions of the new Common Core exams which are being “field-tested” around the country this year. Scores would be not be shared with students, parents or schools because the new tests are being administered on a trial basis.

Gov. Jerry Brown (D) intends to sign the legislation, a spokesman said.

“I feel that a test based on a different curriculum does not make a lot of sense,” Brown told reporters Monday.

Tom Torlakson, the state’s superintendent of public instruction, said in a statement that officials are “guided by what’s right for California’s children. ... Our goals for 21st century learning, and the road ahead, are clear. We won’t reach them by continuing to look in the rear-view mirror with outdated tests, no matter how it sits with officials in Washington.”

Duncan and others acknowledge that using old tests is not ideal but that they still afford some measure of accountability.

“... Letting an entire school year pass for millions of students without sharing information on their schools’ performance with them and their families is the wrong way to go about this transition,” Duncan said in a statement. “No one wants to over-test, but if you are going to support all students’ achievement, you need to know how all students are doing.”

Duncan is backed by Rep. George Miller of California, the ranking Democrat on the House Committee on Education and the Workforce and an author of No Child Left Behind, as well as several advocacy groups including Education Trust-West, StudentsFirst and Democrats for Education Reform.

Thomas Kane, a director of the Center for Education Policy Research at Harvard, said California’s plan to give students field tests but withhold scores is like practicing basketball in the dark. “If you’re going to take a practice shot, it helps to know if the ball goes in the hoop,” Kane said. “If it does not provide results back, California is asking teachers and students to take practice shots in the dark.”

While some governors are having second thoughts about the adoption of the Common Core in the face of political pressure and new costs, Brown has been a steady booster, allocating $1 billion to help teachers and schools enact the new standards.

Supporters of Common Core say the standards are designed to reduce rote memorization and cultivate critical thinking in students. The standards do not dictate curriculum, allowing states to decide what to teach. Participating states have been rolling out the standards at different paces, but all are expected to have them in time for the new exams in the 2014-2015 school year.

Other states have opted to administer their old tests to most students this year while a small portion of their students field test the Common Core exams, the results of which will not be used to evaluate the performance of schools or teachers.

David DeSchryver, an attorney who has represented California in past skirmishes with regulators at the U.S. Department of Education, said the regulatory process is so lengthy that by the time the Obama administration takes action against the state, the new tests will likely be in place.

Still, he said the department is compelled to act because it is trying to hold the line on accountability while much of the country makes a significant shift in the way schools measure progress.

“They’re at this transition and the Department of Education recognizes it has to bridge it, but they don’t want to make a clean break because it would create this chasm in accountability,” DeSchryver said. “They’ve got themselves in a bit of a sticky situation.”