President Barack Obama announced that he is "embarrassed" for the 47 Republican senators who signed an open letter to Iran undermining his credibility in securing a nuclear deal.

"I'm embarrassed for them," Obama said in a video teasing his interview with Vice News on Friday.

"For them to address a letter to the Ayatollah, who they claim is our mortal enemy, and their basic argument to them is, 'Don't deal with our president because you can't trust him to follow through on an agreement,' that's close to unprecedented," Obama said in the interview trailer. The full interview is scheduled to air on HBO on Monday.

All but seven congressional Republicans in the Senate signed the letter, which warns Iran's leaders that any negotiated agreement on their nuclear program could expire once Obama leaves office in 2017. No Democrats signed the letter.

The letter has sparked major backlash from both Democrats and Republicans, along with several newspapers that had originally endorsed GOP senators, reports The Associated Press.

Ohio Sen. Rob Portman was criticized by the Cleveland Plain Dealer and Cincinnati Enquirer, although both papers backed his 2010 campaign.

"The magnitude of this disgraceful decision, shows the degree to which to partisanship has gobbled up rationality on foreign policy," read a Plain Dealer editorial.

The Cincinnati Enquirer's editorial said the letter "diminishes the dignity of the Senate by disparaging the president and presenting an amateur lesson on U.S. governance."

In response to the backlash, some GOP members have expressed regret over signing the letter, like Republican Sen. Ron Johnson of Wisconsin who said, "If there was any regret, tactically, it probably would have been better just to have it be an open letter addressed to no one."

Likewise, Sen. Pat Roberts of Kansas said that the letter "could have been addressed to other folks and gotten the message out," Roberts said. "But I think the message is more important than who we send it to."

Other Republicans have doubled down, saying that it is necessary for their voice to be heard in negotiations because they fear Obama will strike a deal that is too lenient on Iran.

Watch the trailer of Obama's interview with Vice News below.