To a growing list of ways Republicans have tried to undermine President Barack Obama, add writing a letter to Iran’s leaders while the Obama administration is at a critical moment in negotiating a nuclear deal with Tehran. A letter addressed to “leaders of the Islamic Republic of Iran” and signed by nearly four dozen GOP senators Monday drew harsh criticism from the White House and some Democratic senators, who saw the move as a new extreme in the politicization of foreign policy. The letter, signed by 47 Republican senators, warns Iran’s leaders a deal brokered by Obama could be reversed if it's made without congressional approval, the New York Times reported.

White House press secretary Josh Earnest said the senators were overstepping their traditional role of oversight on foreign policy matters and announced the White House would send a rebuttal letter, in the hope Republicans haven’t set back progress in the negotiations. “Writing a letter like this that appeals to the hard-liners in Iran is frankly just the latest in a strategy, a partisan strategy, to undermine the president’s ability to conduct foreign policy and advance our national interests around the world,” Earnest said Monday.

He also linked the letter to Speaker John Boehner’s recent decision to invite Israeli Prime Minister Benjamin Netanyahu to address a joint session of Congress without consulting the White House. In the speech last week, Netanyahu denounced a U.S.-led nuclear deal with Iran. Several prominent Democrats chose not to attend the speech and, on Monday, blasted the senators’ letter.  

“When it comes to preventing Iran from obtaining a nuclear bomb, we should put partisanship aside,” Senate Minority Leader Harry Reid said from the Senate floor Monday. “Throughout the eight years of George W. Bush’s presidency, I disagreed with his foreign policy. I spoke about it on the floor lots of times. But even at the height of our disagreements with President George W. Bush, Senate Democrats never considered sending a letter to Saddam Hussein.”

Sen. Bernie Sanders, Ind-Vt., suggested the Republicans’ letter could have more disastrous consequences. “It appears that for most of my Republican colleagues in the Senate, a war in Afghanistan and a war in Iraq were not enough,” Sanders said. “They now apparently want a war in Iran as well. It is an outrage that my Republican colleagues are trying to sabotage that [negotiating] effort. ”

Sen. Tom Cotton, R-Ark., who drafted the letter, said it was meant to educate Iranian leaders who might not understand the American system of government.

“The next president could revoke such an executive agreement with the stroke of a pen, and future Congresses could modify the terms of the agreement at any time,” said the letter, according to the Times report. In the U.S., international treaties require a two-thirds vote of the Senate for ratification. The agreement Obama and other leaders are negotiating would not automatically go to Capitol Hill, something members of both parties want.