Iran's national security chief has said there is no decision-making consistency in the US government to work towards reentering the 2015 nuclear agreement.

In a tweet on Wednesday, Secretary of the Supreme National Security Council Ali Shamkhani said, “Voices from the US government show that there is no coherence in the country to make political decisions in the direction of advancement in the Vienna Talks”.

He added that “the US administration cannot pay for its internal disputes by violating Iran's legal rights”.

Shamkhani’s comments were in reaction to Republican senators warning that they would work to thwart any new Iran deal if President Joe Biden did not allow Congress to review and vote on any new nuclear deal with Iran.

Led by Senator Ted Cruz, a long-time opponent of the nuclear deal, the senators told Biden in a letter on Monday that they would use "the full range of options and leverage available" to ensure that his government adhered to US laws governing any new accord with Iran.

Republican lawmakers have been warning Biden from the early days of his administration when he criticized his predecessor’s decision to pull out of the Joint Comprehensive plan of Action (JCPOA) and begin talks with Iran to restore the agreement.

Republicans have argued that the JCPOA was a weak arrangement that did not prevent Iran from ultimately acquiring nuclear weapons and did not cover other issues, such as Tehran’s ballistic missiles and its aggressive regional policies through its proxies.