When the terms of the Memorandum of Understanding between the Trump administration and the Iranian government leaked last week, lawmakers from both parties said they looked forward to reviewing it.
Sen. Lindsey Graham (R-S.C.), a strong supporter of the war with Iran, said "any nuclear deal with Iran will be sent to Congress for review and a vote," and that it was "imperative” for Vice President JD Vance, who Graham called “the architect of the deal,” to come to the Hill and present the agreement.
“We’ve got to have a vote of Congress to be able to solidify [a deal] long term,” added Sen. James Lankford (R-Okla.) Sen. Brian Schatz (D-Hawaii), meanwhile, told Semafor that it is "very clear in federal law that the Senate gets to weigh in.” The skepticism from Schatz isn’t altogether surprising given Democrats’ desire to hold President Donald Trump’s feet to the fire ahead of the midterms. But the demand is striking coming from Republican senators who largely stood aside as the administration took the country to war, but now want a formal role in how it ends.
Whether they will actually get a say this time is hard to predict. Though most legal experts believe the administration is bound by law to submit the agreement for review, the White House will likely try every possible maneuver to avoid that outcome. And the politics on Capitol Hill are complicated enough that neither party may have much appetite to push for the vote that many members are publicly demanding. The vehicle for that review would be the Iran Nuclear Agreement Review Act (INARA), a law passed during the Obama-era negotiations that led to the 2015 Joint Comprehensive Plan of Action (JCPOA). The law, which gives Congress discretionary oversight of nuclear deals, has broad language that requires the president to seek immediate authorization regarding any "agreement related to the nuclear program of Iran that includes the United States" and prohibits the president from waiving sanctions on Iran for 30 days to allow for congressional review.
Though the MoU is largely a preliminary agreement, it does include a reiteration of Iran's agreement not to pursue a nuclear weapon and a conditional pledge for the lifting of sanctions. Under INARA, a vote is not automatically triggered — instead requiring members to introduce a resolution of disapproval— and Vice President Vance said Thursday that only parts of the deal required approval and that the administration was “quite confident that we can temporarily lift those sanctions without going to Congress." Trump has said he liked the idea of sending the agreement to Congress for review. The politics on this front are tangled: many Republicans are wary of publicly crossing Trump but are opposed to legitimizing diplomacy with Iran. Many Democrats want to criticize the administration but don't want to be seen opposing a peaceful resolution. Consequently, close observers of Hill dynamics tell RS that the statements are perhaps meant to hurt the prospects of an agreement succeeding, but whatever members say publicly, most lawmakers on both sides would prefer to never vote on the issue, at least until a more comprehensive deal is reached. As Curt Mills, executive director of the American Conservative magazine said in a Quincy Institute press briefing on Monday, Republican hawks may aim to “kill [the deal] in the crib,” but do not want to directly challenge the president.
Pro-Israel groups like the prominent lobbying shop AIPAC and the Jewish Institute for National Security of America, a think tank that has long been an advocate for a war with Iran, have signaled that they see the legislature as the best place to sink a deal. The groups both centered the importance of congressional oversight in their statements about the MoU, and AIPAC listed the bypassing of Congress as one of their “ serious concerns ” regarding the accord. Herein lie some of the medium and longer-term risks that could bring the U.S. back into hostilities with Iran, according to Dylan Williams, the Vice President for Government Affairs at the Center for International Policy.
“For those of us who actually want to see a ceasefire hold and who want to see diplomacy in the right direction with Iran proceed in the future, [the danger] is that Democrats try to make so much political hay of what they see as deficiencies with the deal that they actually establish red lines that are not helpful,” Williams told RS in an interview. There have been examples of such rhetoric from the opposition party in the first days since the MoU was signed. Rep. Brad Schneider (D-Ill.), for example, listed four questions that he hoped the deal would address, including some, such as addressing Iranian “proxies,” that are not part of the preliminary agreement. Other Democrats have suggested or said explicitly that they would not support a deal that includes a $300 billion fund for “the reconstruction and economic development of the Islamic Republic of Iran.” Sen. Ed Markey (D-Mass.), for example, called on Congress to “review and reject this deal immediately.”
Other Democrats have struck a different tone. Rep. Ro Khanna (D-Calif.) has been more careful to separate his criticism of the administration from the diplomatic process itself, urging members of his party to support the agreement. Rep. Joaquin Castro (D-Texas), for his part, reminded Democrats to “not replicate Republicans’ irresponsible opposition to the Obama Administration’s Iran nuclear agreement,” which he says led to the current war. Beyond the risk that overheated language could undermine the diplomatic process, Williams points to a second pressure track: the risk that hawkish lawmakers, particularly Republicans who may fear going directly against the president, could try to “backfill some of the sanctions that are being suspended or even eliminated under the MoU and start pressing for new types of pressure on Iran.”
As happened during the Obama era, Congress can thwart or at least complicate negotiations by continually proposing, and occasionally passing, new forms of pressure on Iran, Williams notes.
During the JCPOA debate, “the notion of sanctions relief for Iran got heavily securitized. And that made it viable for the next presidency to overturn it,” Ryan Costello, policy director at the National Iranian American Council, tells RS. This time around, Costello fears that a similar dynamic could be at play. “If it's maligned so thoroughly, it gets hard to implement,” he says. “Eventually someone comes along and undoes it entirely and we're back to a situation where the U.S. and Iran are either at war or not far away from it.”
In Switzerland on Monday, Vance said that Iran — which had suspended cooperation with the International Atomic Energy Agency following U.S-Israeli strikes against nuclear facilities in June 2025 — would allow the nuclear watchdog back into the country, though the scale and timing of such inspections remained unclear. Kelsey Davenport, Director for Nonproliferation Policy at the Arms Control Association, says that ensuring strong inspections from the IAEA would be one important way to protect the deal from crumbling.
“If the Trump administration cannot certify that an agreement is verifiable, which is a stipulation of INARA, it creates opportunity for Congress to question a deal or try to take action to re-impose sanctions, " Davenport tells RS. “Even if Congress does not succeed in the re-imposition of sanctions, an acrimonious debate over a future deal or continued allegations and rhetoric questioning the verifiability of a deal, can undermine its sustainability.”