Republican Sen. Ted Cruz of Texas said the Widespread Core education requirements are a bad idea and he opposes them unequivocally during an address to an anti-tax group on Friday — a shot across the bow of GOP presidential candidate Jeb Bush, who supports them.

Cruz said Popular Core was essentially a situation where national standards were being “dictated” from Washington. He was speaking at Club for Growth’s annual winter meeting, according to an Associated Press report.

Cruz, who is serving his first team in the U.S. Senate and is mulling a 2016 presidential campaign, said that there is “no remedy” when Washington is “dictating what’s becoming taught to your children,” according to the report.

Bush, the frontrunner for the 2016 GOP presidential nomination, told the same group that the education targets would aid far more students, who would be much better equip to transition to college or find a good job.

Popular Core refers to a set of requirements that set voluntary goals in math, reading, and language arts. They were created by a group of governors from both the Democratic and Republican parties, and 40 states have adopted those standards.

However, once the Obama Administration endorsed them, many Republicans began lining up to reject them.

Bush was not one of them, arguing that Common Core standards was not a federal takeover of education as some have argued, and said that the federal government doesn’t have any role in the creation of the requirements, directly or indirectly.

A total of six potential GOP presidential candidates, including Cruz and Bush, are schedule to speak at the Club for Growth’s winter meeting, which will end Saturday. Also scheduled to speak are Wisconsin Gov. Scott Walker, Indiana Gov. Mike Pence, Florida Sen. Marco Rubio, and Louisiana Gov. Bobby Jindal.