With Sen. Tom Cotton presiding over the Senate, the chamber’s Democratic leaders lambasted the open letter  the Arkansas Republican spearheaded with 46 other Republicans to the leadership of Iran.  

In the letter, the Republican senators told the Iranian leaders that any agreement about the country’s nuclear program reached with the United States and the other negotiating partners might well not last beyond President Barack Obama’s time in the White House, citing the separation of powers.

“What these two constitutional provisions mean is that we will consider any agreement regarding your nuclear-weapons program that is not approved by the Congress as nothing more than an executive agreement between President Obama and Ayatollah Khamenei. 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,” the senators wrote. “We hope this letter enriches your knowledge of our constitutional system and promotes mutual understanding and clarity as nuclear negotiations progress.”

When the Senate convened Monday, Minority Leader Harry Reid criticized Cotton’s effort, noting the Republican had only served in the Senate for roughly two months before leading the letter and saying his Democrats did not take similar action during President George W. Bush’s administration.  

“Even at the height of our disagreements with President George W. Bush, Senate Democrats never considered sending a letter to Saddam Hussein or other Iraqi leaders at the time,” Reid said. “Never considered it.”  

“The stakes really couldn’t be higher. We as leaders should do everything we can to help these negotiations succeed. When it comes to preventing Iran from obtaining a nuclear bomb, we should put partisanship way to one side. Sadly though, the judgment of my Republican colleagues seems to be clouded by their abhorrence of President Obama,” Reid said. “Let’s be very clear: Republicans are undermining our commander-in-chief while empowering the ayatollahs.”  

There’s bipartisan support in the Senate for legislation introduced by Foreign Relations Chairman Bob Corker that would require an eventual agreement with Iran to be submitted for congressional review. But action has been delayed until March 24, since a group of Democrats do not want to move forward before that. Corker, a Tennessee Republican, did not sign Cotton’s letter, which was reported Sunday night by Bloomberg.  

But other Democrats joined Reid in expressing outrage about the GOP letter, including Sen. Dianne Feinstein of California, who leads her party on the Intelligence Committee.  

“I am appalled at the latest step of 47 Republicans to blow up a major effort by our country and the world powers to negotiate a peaceful resolution to the Iranian nuclear program,” Feinstein said. “This is a highly inappropriate and unprecedented incursion into the president’s prerogative to conduct foreign affairs and is not befitting this chamber. This letter only serves one purpose — to destroy an ongoing negotiation to reach a diplomatic agreement in its closing days.”  

In fact, Cotton has long indicated he would prefer the current negotiations with Iran fail to yield an agreement, as he said at a Heritage Action event in January.  

“The end of these negotiations isn’t an unintended consequence of congressional action. It is very much an intended consequence,” Cotton said.  

Senate Minority Whip Richard J. Durbin joined Reid in an exchange on the floor after issuing his own statement critical of the letter.  

“Understand that if these negotiations fail, a military response to Iran developing their nuclear capability becomes more likely,” said Durbin, an Illinois Democrat, in his statement. “These Republican Senators should think twice about whether their political stunt is worth the threat of another war in the Middle East.”  

Across town at the White House, Press Secretary Josh Earnest accused Republicans of advocating a “rush to war, or at least the rush to the military option.”  

Steven T. Dennis contributed to this report. The 114th: CQ Roll Call’s Guide to the New Congress Get breaking news alerts and more from Roll Call in your inbox or on your iPhone.