OREANDA-NEWS. A trio of Republican presidential hopefuls cautioned against repudiating the Iran nuclear deal outright during last night's presidential debate, differentiating themselves from some fellow candidates and many Republicans in Congress.

Taking the stage with eight other presidential contenders for a prime-time, Republican debate, Jeb Bush, John Kasich and Rand Paul took issue with rivals' promises to revoke immediately the agreement the US and other global powers reached with Iran, swapping nuclear concessions for oil and petrochemical sanctions relief.

Texas senator Ted Cruz last night reiterated his vow to "rip to shreds this catastrophic Iranian nuclear deal" on his first day in the Oval Office, while Wisconsin governor Scott Walker claimed to have been "one of the first ones to call for terminating the bad deal with Iran on Day One."

Former Florida governor Bush argued that "it is not a strategy to tear up an agreement," however. "A strategy would be: How do we confront Iran? And, the first thing that we need to do is to establish our commitment to Israel, which has been altered by this administration." Bush, whose father and brother have both served as president, said he would ensure Israel has sophisticated weaponry "to send a signal to Iran that we have Israel's back."

Kasich, a former member of the US House of Representatives and now governor of Ohio, has been criticizing Cruz on the campaign trail for pledging to shred the agreement. He has said any candidate who promises to rescind the deal immediately is demonstrating inexperience and "playing to a crowd."

Last night, Kasich called the deal a "bad agreement," and said "I would never have done it." But he added, "We do not know what is going to happen in 18 months." And he warned about the dangers of trying to operate on the world stage alone, without the help of the US' traditional allies.

And Kentucky senator Paul said it would be "absurd" to cut up the Iran agreement immediately. "Would you want to know if they complied?" Paul asked.

Paul said he opposes the deal President Barack Obama's administration helped to negotiate. "But it does not mean that I would immediately not look at the agreement."

Such fissures in the Republican ranks over the Iran deal have not been as evident on Capitol Hill, where no Republican has voted in favor of the agreement. Senate Democrats twice have blocked Republicans from bringing a resolution of disapproval up for a vote.

Today, the Senate is poised to take up an amendment sponsored by Senate majority leader Mitch McConnell (R-Kentucky) that would bar Obama from lifting any sanctions on Iran until Tehran formally recognizes Israel's right to exist and until it releases US citizens held in Iran.

The White House contends the congressional review period for the Iran deal expires today. But the Republican-controlled US House of Representatives passed a nonbinding resolution asserting that the review period has yet to begin, since the administration has not turned over documents pertaining to the UN nuclear watchdog IAEA's agreements with Tehran.

EU and US sanctions have limited Iran's crude exports to 1.1mn b/d, down from about 2.5mn b/d before they were imposed in 2012. Iran produced 2.86mn b/d in August, down from 2.88mn b/d in July, making it Opec's fourth-largest oil producer.