Rep. Tom Cotton (R-) is campaigning to unseat U.S. Sen. Mark Pryor (D) in Arkansa. (AP Photo/Danny Johnston)

Rep. Tom Cotton (R-Ark.) said in an interview broadcast Tuesday that President Obama made a "grievous error" when he agreed to release five prisoners held at Guantanamo Bay to secure the release of U.S. Army Sgt. Bowe Bergdahl from Taliban custody, echoing the concerns of many other congressional Republicans.

"I think the president made a grievous error by negotiating with terrorists and engaging in a prisoner swap," Cotton said on the podcast of KNWA Today anchor J.R. Davis.

Cotton is the Republican nominee challenging Sen. Mark Pryor (D-Ark.) in key race in the battle for the Senate majority. Cotton, an Iraq war veteran, said he thinks Obama's decision endangers the lives of other American troops. "There is now a price on the head of American hostage. And Barack Obama has helped put that price there," he said.

Bergdahl was released from Taliban custody Saturday after nearly five years in captivity. In exchange, the U.S. government released five Afghan inmates, who must remain in Qatar for at least a year.

Some Republican lawmakers are concerned that Congress was not notified in advance of the release as required by law and about the precedent the deal could set. They have vowed hearings into the matter.  Obama defended his decision Tuesday, saying, "We saw an opportunity, and we were concerned about Bergdahl’s health."

Cotton said that if he had been in Obama's position, he would have "continued to use intelligence and special operations units to try to retrieve" Bergdahl.