The White House on Wednesday said "right-wingers" in both the U.S. and Iran are "making the same argument" in order to derail last year's nuclear agreement.

The comments followed a Wednesday letter sent by Arkansas Republican Sen. Tom Cotton earlier demanding details on $400 million the United States reportedly delivered to Iran in secret last year, which called it a "ransom to the ayatollahs."

"It sounds to me like they are once again in a position where they're making the same argument as hardliners in Iran in an effort to undermine the Iran nuclear agreement," White House Spokesman Josh Earnest told reporters when asked. "The president made clear a year ago that right-wingers in the United States were making common cause with right-wingers in the Iranian government."

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Earnest said Cotton's new letter had the same purpose as one he sent to Iran in 2015, which warned Iran Supreme Leader Ayatollah Ali Khamenei that the next president could revoke the deal "with the stroke of a pen."

"If they're doing it again to try to justify their opposition to an agreement that has benefited the American people, they can do that," Earnest said. "But I think that's going to be pretty hard for them to explain. Maybe there's another letter from Sen. Cotton to the supreme leader we don't know about."

The exchange follows a report that the Obama administration airlifted $400 million in cash at about the same time Iran released four Americans detained in Tehran. The administration insists that payment wasn't ransom, and was transferred as part of a settlement for a failed arms deal dating back to 1979.