Sen. Lindsey GrahamLindsey Olin GrahamTrump selects South Carolina lawyer for impeachment trial Democrats formally elect Harrison as new DNC chair McConnell proposes postponing impeachment trial until February MORE (R-S.C.) says President Obama is about to "unleash hell" on the Middle East through a nuclear deal with Iran. 

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Graham, a leading critic of Obama's foreign policy who might run for president, said Arab states and Israel are not going to allow Iran to have a nuclear capability checked only by the United Nations. 

"So Obama is about to unleash hell on the Mideast," he said on the "Hugh Hewitt Show." "He’s about to create a nuclear arms race by wanting a deal with the Iranians so badly that he’s about to make the mistake of a lifetime."

Graham is a major proponent of congressional efforts to pass new sanctions that would take effect if Iran walks away from negotiations, a move the Obama administration opposes as imperiling the talks. 

The Obama administration scored a victory when congressional Democrats, led by Sen. Robert MenendezRobert (Bob) MenendezSenate presses Biden's pick for secretary of State on Iran, China, Russia and Yemen Year-end deal creates American Latino, women's history museums Lawmakers call for including creation of Latino, women's history museums in year-end spending deal MORE (N.J.), backed down last month and said they would wait to support the new sanctions until after the March 24 deadline for the outlines of an agreement with Iran.

Graham, also a supporter of strong action against militants from the Islamic State in Iraq and Syria (ISIS), said it is "not even close" that Iran is a greater threat than ISIS.

"Iran with a nuclear capability is the greatest threat the world will know in my lifetime," he said. 

The South Carolina Republican said Thursday morning on Fox's "America's Newsroom" that the "Ayatollahs are taking the community organizer, law professor, our commander and chief to the cleaners when it comes to the nuclear negotiations."

Graham added that Syrian President Bashar al-Assad is a “puppet of the Iranians” and that Arab fighters on the ground are reluctant to fight ISIS militants unless the coalition commits to removing Assad from power as well.

“The whole goal here should be to liberate Syria not only from ISIL, but from Iranian influence and domination that’s seen by Assad,” he said, using an alternate acronym for the terror group.

— Ben Kamisar contributed to this report, which was updated at 10:52 a.m.