An open letter to Iran signed by 47 Republican senators warning that a nuclear deal with the US may not stick was meant as a tongue in cheek reminder of Congressional power, several GOP aides reportedly said Tuesday, as some in the party distanced themselves from the missive amid intense anger over the move from across the aisle.

Two Republican congressional aides quoted by the Daily Beast in an article published Tuesday described the letter as “cheeky,” while others said the note was a lighthearted attempt as asserting Congressional power vis-a-vis the high stakes talks over a nuclear agreement with Iran.

“The administration has no sense of humor when it comes to how weakly they have been handling these negotiations,” a senior Republican aide was quoted as saying in the Daily Beast.

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Democratic leaders, including President Barack Obama, have expressed deep annoyance over the letter, drafted by Freshman senator Tom Cotton and signed by 47 of the Senate’s 54 Republicans.

Some have gone as far as accusing the senators of illegally contacting Iran or trying to help the regime in Tehran.

In the letter to Iran, Republican lawmakers warned that unless Congress approved it, any nuclear deal they cut with Obama could expire the day he walks out of the White House. Among the signers were members of the leadership and potential presidential candidates.

On Monday, Obama accused the senators of “wanting to make common cause with the hardliners in Iran.”

White House spokesman Josh Earnest said it reflected a “rush to war, or at least the rush to the military option.”

In a statement issued late Monday night, Biden said Republicans had “ignored two centuries of precedent” and he said the move “threatens to undermine the ability” of any future president to negotiate with foreign countries.

Biden, in his statement, noted that presidents of both political parties have negotiated historic international agreements. “Diplomatic recognition of the People’s Republic of China, the resolution of the Iran hostage crisis, and the conclusion of the Vietnam War were all conducted without congressional approval,” he noted.

Former Secretary of State Hillary Rodham Clinton also weighed in, saying Republicans were either trying to help the Iranians or hurt Obama.

Iranian Foreign Minister Mohammed Javad Zarif was quoted by the website of Iranian state TV on Tuesday as saying the letter’s warning that any nuclear deal could be scrapped once Obama leaves office suggests the United States is “not trustworthy.”

He called the letter “unprecedented and undiplomatic.”

Cotton denied undermining Obama’s negotiating position. Appearing on MSNBC, he said, “We’re making sure that Iran’s leaders understand that if Congress doesn’t approve a deal, Congress won’t accept a deal.”

However, a number of Republicans are now seeking to distance themselves from the letter, according to the Daily Beast.

“I immediately knew that it was not something that, for me anyway, in my particular role, was going to be constructive,” Sen. Bob Corker, who heads the Senate Foreign Relations Committee, told the outlet.

However, Corker also blamed Obama for pushing the senators to send the letter, by leaving Congress out of the loop on the nuclear talks.

“I think that, no doubt, the fact that the president, you know, issued a veto threat on a very common-sense piece of legislation, probably evoked, you know, a good deal of passion,” he was quoted telling the Huffington Post.

The Republican-drafted letter was an aggressive attempt to make it more difficult for Obama and five world powers to strike an initial agreement by the end of March to limit Iran’s nuclear program, which Tehran insists is for peaceful purposes.

Republicans worry that Iran is not negotiating in good faith and that a deal would be insufficient and unenforceable, allowing Iran to eventually become a nuclear-armed state.

They have made a series of proposals to undercut or block it — from requiring Senate say-so on any agreement to ordering new penalty sanctions against Iran to threats of stronger measures.

The letter, which had been first distributed by Senate staffers in early March according to the Daily Beast, came on the heels of a controversial speech to Congress on thwarting an emerging deal with Iran by Prime Minister Benjamin Netanyahu which was roundly criticized by Democrats but welcomed by most Republicans.

On Tuesday, Netanyahu said his speech had led to a greater understanding of the issue, which some saw as him hinting he had inspired the letter.

“One week after my address to Congress I get the impression that there are more and more voices, especially in the US, but also in other places, that support Israel’s position,” Netanyahu said.

However, there are fears that the speech and letter have both made the Iranian negotiations into a partisan issue.

On Tuesday, Republican Senator Jeff Flake, who did not sign the letter, said the threat of a nuclear Iran was too important to let it divide lawmakers along partisan lines.

Senator Tim Kaine, a democrat who was one of dozens of lawmakers to skip out on netanyahu’s speech, decried the letter as a partisan “sideshow.”

“Is the Senate capable of tackling challenging national security questions in a mature and responsible way?” he asked.

AP contributed to this report