US Sen. Lindsey Graham (R-SC), speaking in the Dirksen Senate office building in Washington, DC, on July 15, 2025. Photo: IMAGO/MediaPunch via Reuters Connect

Conservative thought leaders and lawmakers have suggested that the controversial US-Iran Memorandum of Understanding (MOU) could be derailed by Congress, citing intense internal turmoil over the deal within the Republican Party.

The White House has transmitted the agreement to Capitol Hill, beginning what is expected to be weeks of scrutiny over its substance and legality.

While the administration insists the memorandum is merely an interim framework, critics argue its practical effect — particularly its commitment to sanctions relief in exchange for future negotiations — could require congressional approval under existing law.

Under the proposed MOU, Iran would reopen the Strait of Hormuz to commercial shipping, cooperate with the International Atomic Energy Agency (IAEA) on its highly enriched uranium stockpile, and commit not to pursue nuclear weapons.

In exchange, Washington would lift its blockade on Iranian ports, suspend certain sanctions, facilitate Iran’s return to global oil markets, and launch negotiations over a broader agreement during a 60-day window.

Critics say the most immediate legal obstacle concerns the Iran Nuclear Agreement Review Act (INARA), enacted in 2015 following congressional opposition to the Obama administration’s Joint Comprehensive Plan of Action (JCPOA) — the technical name for the 2015 Iran nuclear deal. INARA requires Congress to review certain nuclear agreements with Iran before statutory sanctions can be lifted.

Whether the new memorandum qualifies under INARA remains contested. Some legal scholars argue that because it is styled as an interim political understanding, it may fall outside the statute. Others contend that if it effectively commits the US to sanctions relief in exchange for Iranian nuclear commitments, INARA applies.

Experts also warn that the executive branch lacks the authority to permanently erase sanctions without congressional consent — and Iran has long sought precisely that permanent assurance, not simply temporary waivers vulnerable to reversal by future administrations.

The Iran Sanctions Act is scheduled to expire at the end of 2026. Many lawmakers are already discussing extending it before that deadline, which would preserve one of Washington’s most significant sources of leverage over Tehran and signal that Congress has little appetite for relaxing pressure on the Iranian regime.

Another unresolved issue concerns the Islamic Revolutionary Guard Corps (IRGC). Although the memorandum does not publicly require removing the IRGC from the State Department’s Foreign Terrorist Organization list, analysts believe meaningful normalization of economic relations with Iran would become significantly more difficult without doing so.

The memorandum arrives after months of conflict in which Israel and the United States carried out unprecedented military operations against Iran’s nuclear infrastructure. Many Republicans, along with numerous Democratic Iran hawks, argue that military pressure created an opportunity to demand the irreversible dismantlement of Iran’s nuclear program rather than what they view as unenforceable promises from the Iranian regime.

Supporters counter that the MOU is not final or binding, and that diplomacy backed by credible military pressure offers the best chance of preventing an Iranian nuclear weapon while avoiding another major Middle East war.

Senate Armed Services Committee Chair Sen. Roger Wicker (R-MS) launched a sharp attack on the deal, warning that allowing Tehran to have a $300 billion reconstruction package “would make Iran’s payoff under President Obama’s 2015 deal look like a pittance by comparison.”

Sen. Tom Cotton (R-AR), one of the staunchest defenders of Israel in Congress, called Iran a “terrorist regime” and warned that “certain aspects of this deal are a step in the wrong direction.” He also cautioned that Iran could generate “between $150 million to $200 million dollars per day” from lifted oil sanctions.

Sen. Lindsey Graham (R-SC) walked back his initial condemnations of the deal following conversations with the White House, expressing cautious optimism while stressing the need to secure the dismantlement of Iran’s nuclear program.

“Whether or not the United States can reach an acceptable, verifiable deal with Iran regarding its nuclear program and other issues is yet to be determined, but I see little downside to trying,” Graham wrote.