Sen. John McCain, R-Ariz., is urging Agriculture Secretary Sonny Perdue to delay a program to inspect Asian catfish imports, saying its "true purpose" is to erect a trade barrier "at the command of a handful of domestic catfish farmers in southern states."

In a letter, Sen. McCain blasted program as "a classic example of shortsighted, anti-free market protectionism at its worst," and asks for a delay of implementation "until Congress has an opportunity to reverse this duplicative, wasteful program."

The U.S. Department of Agriculture program is set to take effect next month and would heavily regulate imported catfish, The Hill reported.

"The true purpose of the Catfish Inspection Program is to erect a trade barrier against Asian catfish imports at the command of a handful of domestic catfish farmers in southern states," McCain charged.

According to a news release from McCain's office, the Food and Drug Administration traditionally has been tasked with oversight of all fish, including catfish. But a provision included in the 2008 Farm Bill removed FDA oversight of only catfish, transferring inspection responsibilities to the Food Safety and Inspection Service within the Department of Agriculture.

Free-trade advocate McCain earlier this year criticized President Donald Trump's decision to withdraw from the Trans-Pacific Partnership, The Hill noted.