A group of 33 Republican senators led by Sen. Ted Cruz, R-Texas, are arguing that any new nuclear deal with Iran requires Senate approval, warning President Biden that they will do everything in their power to block one if he moves forward without them.

In a letter to Biden sent Monday, the senators asserted that any Iran nuclear deal should be considered a treaty due to its inherent "gravity for U.S. national security," and thus requires two-thirds of the Senate to agree to it.

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"We write to call attention to a range of obligations that your administration is statutorily mandated to fulfill in relation to Congressional oversight over any such agreement," the letter said. "[W]e are committed to using the full range of options and leverage available to United States Senators to ensure that you meet those obligations, and that the implementation of any agreement will be severely if not terminally hampered if you do not."

The senators stated that a "genuinely robust" deal with Iran would get Senate approval, and therefore "the only reason not to present it for a resolution of ratification is that it is too weak to pass muster."

Any deal that does not have Senate approval, they continued, would be "subject to being reversed" as soon as there is a new president.

They went on to note that the Iran Nuclear Agreement Review Act of 2015 (INARA) requires the administration to submit any deal to Congress for review within five days of it being reached. Such agreements, they said, would include "concessions" to the Islamic state. On Friday, the Biden administration restored civil nuclear waivers for international nuclear cooperation with Iran, but the State Department insisted this was "not a concession to Iran"

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INARA would also be triggered, the letter said, by a return to terms of the original Iran nuclear agreement entered into by the Obama administration known as the Joint Comprehensive Plan of Action (JCPOA).

However, they warned, a more far-reaching deal is now needed due to Iran’s continued nuclear activities.

"On the Iranian side, during the first year of your administration, the regime has made qualitative progress toward a nuclear arsenal that requires new measures to reverse, far beyond anything envisioned by the JCPOA," the letter said.

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Fox News reached out to the White House for comment, but it did not immediately respond.

The other senators who joined Cruz in signing the letter are Sens. Bill Hagerty, R-Tenn., Tom Cotton, R-Ark., Chuck Grassley, R-Iowa, Roger Marshall, R-Kan., Thom Tillis, R-N.C., Marco Rubio, R-Fla., Tim Scott, R-S.C., Bill Cassidy, R-La., Mike Braun, R-Ind., Rick Scott, R-Fla., Cynthia Lummis, R-Wyo., Roger Wicker, R-Miss., Joni Ernst, R-Iowa, John Boozman, R-Ark., Ron Johnson, R-Wis., John Barrasso, R-Wyo., Todd Young, R-Ind., Cindy Hyde-Smith, R-Miss., Kevin Cramer, R-N.D., Jim Inhofe R-Okla., John Hoeven, R-N.D., Ben Sasse, R-Neb., Steve Daines, R-Mont., Pat Toomey, R-Pa., John Kennedy, R-La., John Cornyn, R-Texas, Rob Portman, R-Ohio, Marsha Blackburn, R-Tenn., Mike Lee, R-Utah, John Thune, R-S.D, Jim Risch R-Idaho, and Dan Sullivan, R-Alaska.

Fox News' Hannah Grossman contributed to this report.