Republican senators warned US President Joe Biden that if the US reaches any nuclear deal with Iran and does not allow Congress to review and vote on its terms, they would work against the accord and foil it.

33 senators, led by Texas Senator Ted Cruz - who has long opposed the JCPOA from which Trump withdrew - told Biden on Monday they would use "the full range of options and leverage available" to ensure that Washington abided by US laws concerning the formulation of an accord with Tehran.

The United States and major world powers are currently trying to reach an agreement about Iran's nuclear program, which resumed after the Trump administration withdrew from an agreement curbing it in 2018. Trump not only abandoned all obligations but also imposed harsh sanctions on Iran, leading Tehran to go back on its nuclear pledges.

The Republican senators told Biden they would "severely, if not terminally hampe[r]" the implementation of any new Iran nuclear deal if his administration did not meet statutory obligations aimed at ensuring that Congress oversees any revisions or changes to the 2015 nuclear agreement.

The senators did not disclose what their plans entailed, but over time they have proven to be a thorn in Biden's side, thwarting his legislations or nominees for various posts.

Though democrats technically have the majority in the senate - the senate has 50 Democratic senators and 50 Republicans, but Vice President Kamala Harris has a tie-breaking vote - they could lose the Senate and the House of Representatives in this year's November elections.

They argued any agreement with Iran that had "such gravity for US national security" would be a treaty by definition, which would require the advice and consent of at least two-thirds of the Senate.

They also warned Biden that any deal not ratified by the Senate would "likely be torn up in the early days of the next presidential administration."

In the letter, they reminded Biden of a 2015 law passed ahead of the signing of the JCPOA, which stipulated that any accord related to the Iranian nuclear program be passed through Congress for a 60-day review period, during which the body could either disapprove of the deal preventing it from going into effect, amend it, or approve of it as it is.