Iran’s Foreign Minister Mohammad Javad Zarif quickly tried to quash an open letter from 47 US Republican Senators on Monday, saying their warnings over a possible nuclear agreement between Tehran and Washington were a “propaganda ploy”.

The Senators had chided, “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.”

Rebuffing the prospect that Congress could block a settlement between Iran and the 5+1 Powers (US, Britain, France, Russia, China, and Germany), Zarif replied, “The world is not the United States, and the conduct of inter-state relations is governed by international law, and not by US domestic law.”

The Foreign Minister said, “While negotiations are still in progress and while no agreement has been reached, some political pressure groups are so afraid even of the prospect of an agreement that they resort to unconventional methods, unprecedented in diplomatic history.” He linked the Senators to the opposition of Israel’s Prime Minister Benjamin Netanyahu, “who considers peace as an existential threat”.

Responding to the specific claim that Obama’s executive agreement to a deal applies only while he is in office, Zarif asserted, “A change of administration does not in any way relieve the next administration from international obligations undertaken by its predecessor in a possible agreement about Iran’s peaceful nuclear program.”

President Obama also had some sharp words for the Republican legislators: “I think it’s somewhat ironic to see some members of Congress wanting to make common cause with the hard-liners in Iran. It’s an unusual coalition.”

Iran and the US, as well as high-level officials from the European Union, resume discussions on Sunday in Switzerland. Intense discussions since January have narrowed gaps over Tehran’s uranium enrichment, but the timing of the lifting of US-led sanctions is still being disputed.

The Secretary of the National Security Council, Ali Shamkhani, reiterated on Monday at a naval ceremony in northern Iran:

The speculations that Iran needs a deal at any price is the result of the other side’s miscalculations and is wrong.

The only way to reach a nuclear agreement is through mutual interests and removal of all sanctions.