Nearly 200 House Republicans have written to President Joe Biden warning that any nuclear deal made with Iran without Congress' approval "will meet the same fate" as the 2015 agreement.
The letter was first published on Wednesday on the Axios news website.
The Biden administration has been working feverishly to secure an agreement via indirect nuclear talks in Vienna, but on Wednesday, an Iranian official publicly called for Congress to pledge that the US will stay in a potential deal.
The GOP letter — signed by most members of the party that polls say will run the House next year — bluntly rebuffs Iran's request.
"We will view any agreement reached in Vienna which is not submitted to the US Senate for ratification as a treaty — including any and all secret agreements made with Iran directly or on the sidelines of official talks — as non-binding," the GOP lawmakers wrote to Biden, according to Axios.
The letter also lays out conditions to which Iran's leaders would likely never agree.
The Republicans promise to oppose any agreement that lifts US sanctions on Iran unless the Iranian regime has first fully dismantled all its enrichment capabilities.
They also want Iran to destroy its nuclear-capable missiles, halt all sponsorship of terrorism and pay "US federal court judgments owed to the American victims of terrorism sponsored by the Iranian regime."
The letter was signed by 175 House Republicans, led by Reps. Mike Gallagher (R-WI) and Michael Waltz (R-FL). House Minority Leader Kevin McCarthy signed it, as did Rep. Liz Cheney (R-WY).
A State Department spokesperson told Axios, "The Biden administration is not negotiating a return to mutual compliance with the JCPOA based on who is in office in Iran today or tomorrow, and we would expect the same approach from Iran."
The letter comes as talks to revive the 2015 deal with Iran, which resumed in Vienna several days ago, continue.
On Wednesday, Iran's top nuclear negotiator, Ali Bagheri Kani, said that an agreement between Iran and world powers is closer than ever.
"After weeks of intensive talks, we are closer than ever to an agreement; nothing is agreed until everything is agreed, though," he said, according to Reuters.