WASHINGTON - Former U.S. Secretary of State Hillary Clinton said a letter by 47 Republican senators sent directly to Iran's government "was out of step with the best traditions of American leadership" and undermined sensitive, international talks with the Islamic Republic to curb its nuclear program.
"Either these senators were trying to be helpful to the Iranians or harmful to the commander-in-chief in the midst of high-stakes international diplomacy," Clinton said in a news conference Tuesday at the United Nations. "Either answer does discredit to the letter's signatories."
Clinton had served in the Senate, representing New York State, from 2001 until becoming the nation's chief diplomat in 2009, appointed by President Barack Obama.
Her comments added to those of Vice President Joe Biden and other Democrats chastising the Republican senators.
They said an signed by the lawmakers could damage the diplomatic talks, adding that it is a move tantamount to rushing to war with Tehran.
The letter comes just weeks before a late-March deadline for the so-called P5+1 world powers to reach a deal with Iran. Besides the United States, they include China, France, Germany, Russia and the United Kingdom.
Biden, who was a senator for 36 years, said the letter threatens to undermine the ability of future presidents to negotiate international agreements and "is beneath the dignity of an institution I revere."
"This letter sends a highly misleading signal to friend and foe alike that our commander-in-chief cannot deliver on America's commitments – a message that is as false as it is dangerous," Biden wrote in a statement late Monday.
He said the senators also offered "no viable alternative" to the ongoing nuclear negotiations.
The Republicans' letter warned any nuclear agreement could be modified or revoked once Obama leaves office in early 2017.
A prominent political scientist said that while the letter is extraordinary and unusual, it is legitimate for the lawmakers to write it.
The letter, authored by freshman Arkansas Senator Tom Cotton and co-signed by 46 other lawmakers, seeks to inform Iran’s leaders that any nuclear agreement involving the United States could face constitutional hurdles.
It states that, while the president can negotiate international agreements, Congress plays "a significant role" in ratifying them. It says a so-called congressional-executive agreement requires a majority vote in both the House of Representatives and the Senate, where a three-fifths majority of 100 senators is needed.
The letter also warned that any agreement regarding Iran’s nuclear weapons program that is not approved by the Congress will be viewed as nothing more than an executive agreement that could be revoked by a future president or modified by Congress.
Iran’s foreign minister, Mohammed Javad Zarif, denounced the letter Tuesday as having "no legal value" and dismissed it as "mostly a propaganda ploy." He said "the conduct of inter-state relations is governed by international law and not by U.S. domestic law."
"This kind of communication is unprecedented and undiplomatic," Zarif was quoted as saying by a state-run TV website. "In fact, it implies that the United States is not trustworthy" if any nuclear deal could be scrapped once Obama leaves office.
Zarif warned future revocation of any agreement "would be a blatant violation of international law."
The letter seemed to harden partisan lines in the Senate, where Republicans will need Democrats' support to pass legislation now in the works to tighten sanctions on Iran or require congressional approval of a deal.
Senate Democratic Leader Harry Reid spoke out against the Republicans' "unprecedented" intervention in sensitive international negotiations "with the sole goal of embarrassing the president of the United States."
"This is a cynical effort by Republican senators to undermine sensitive international negotiations. It weakens America's hand and highlights our political divisions to the rest of the world," said Richard Durbin, the Senate's No. 2 Democrat.
A spokeswoman for Cotton said his office had invited several Democrats to co-sign but none had done so.
Senate Majority Leader Mitch McConnell's signature is on the letter; he said lawmakers should be suspicious of an administration that is intent on keeping Congress out of the emerging deal with Iran.
Several prospective presidential candidates also signed, including Republican Senator Marco Rubio of Florida. He said he would "sign the letter again tomorrow," calling it an extraordinarily important matter.