At a Senate Foreign Relations Committee hearing, Sen. Marco Rubio (R-Fla.) said he hoped the next president would reject the Obama administration's deal with Iran. Secretary of State John Kerry said he didn't think that would be the case. (AP)

The Obama administration and Senate opponents of its nuclear deal with Iran drew hard lines during an acrimonious opening hearing on the accord Thursday, leaving little apparent room for compromise.

Republicans gave long and often scathing speeches denouncing what they described as a fatally flawed agreement and accusing the administration of dangerous naivete. They showed little interest in responses from Secretary of State John F. Kerry, Energy Secretary Ernest Moniz and Treasury Secretary Jack Lew.

Kerry seemed scarcely able to contain his incredulity and impatience with members of a committee he once chaired, saying that critics don’t understand the deal or the potential consequences of rejecting it.

“I believe you’ve been fleeced,” Foreign Relations Committee Chairman Bob Corker (R-Tenn.) told Kerry. Iran, he said, had gone from being “a rogue nation that had a boot on its neck” with crippling international sanctions to a country that would reap a windfall from sanctions relief and be allowed to develop an “industrial”-strength nuclear program.

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Others called elements of the agreement “ludicrous” and said U.S. negotiators, led by Kerry, had been “bamboozled.” Sen. Marco Rubio (R-Fla.), who is running for his party’s presidential nomination, said that “this is a deal whose survival is not guaranteed” beyond President Obama’s term in office, when he hoped the next president would reverse it.

Kerry scoffed at the notion that there was a better deal to be had, calling it a “fantasy, plain and simple . . . some sort of unicorn arrangement involving Iran’s complete capitulation.”

If the United States were to walk away from the multi­lateral agreement it negotiated with five global partners, he said, “we’re on our own.”

“Our partners will not walk away with us,” he said, and “we will have squandered the best chance we have to solve this problem through peaceful means.”

At stake is a landmark agreement finalized between Iran and world powers last week that would require Tehran to remove the vast majority of its stockpile of enriched uranium, dismantle much of its nuclear infrastructure and submit to regular inspections of nuclear sites — all in exchange for relief from economic sanctions.

Republican opponents seeking to derail the deal would need to secure a two-thirds vote in both chambers to override a veto pledge from Obama. It remains unclear whether GOP critics could surmount that obstacle, but if they succeeded, U.S. sanctions on Iran would remain in place and an agreement that Obama regards as a signature foreign policy achievement would probably collapse.

The accord has encountered similar opposition in Iran, where President Hassan Rouhani on Thursday faced down hard-liners, calling the deal a “valuable” step for his country that would ease sanctions and reopen Iran’s struggling economy.

At a Senate Foreign Relations Committee hearing, Secretary of State John Kerry predicted that the nuclear deal with Iran would keep that nation peaceful, saying it is "a good deal for the world." (AP)

“This is a new page in history,” Rouhani said in a nationally broadcast speech.

The White House has launched an intense lobbying effort to fend off criticism that the agreement will fail to eliminate Iran’s uranium-enrichment capability, will allow key restrictions to lapse after 10 to 15 years, and will put the burden on inspectors to uncover cheating and to try to prove those allegations during a 24-day dispute resolution period in which some believe Iran could seek to hide evidence.

Kerry, Moniz and Lew have held closed-door briefings for lawmakers and will testify in the House next week. Pro-Israel groups and Israel itself are lobbying against it, while more-liberal U.S. Jewish groups are pressing for its approval. Diplomats from France, Britain and Germany — who negotiated with the United States — are also making the rounds on Capitol Hill to advocate for the agreement.

Defense Secretary Ashton B. Carter has had discussions about the deal during his current trip to the Middle East, where Israel has expressed outright rejection and Arab allies have voiced skepticism.

The administration got a boost Thursday when Saudi Foreign Minister Adel al-Jubeir told reporters that the deal appears to have the provisions necessary to curtail Iran’s ability to obtain a nuclear weapon, the Associated Press reported.

Jubeir said the kingdom had been reassured by U.S. explanations about inspections and the ability to reinstate sanctions if Iran violates the agreement. “We are currently in talks with the American government regarding these details,” he said, “but it generally seems to have achieved these objectives.”

Congress has 60 days to review the deal and decide whether to try to stop it. Lawmakers will be on their summer recess through most of that period, which expires in late September. Implementation is scheduled to begin in mid-October, with Iran’s completion of its initial obligations — and the lifting of all sanctions — to come six months after that.

While Kerry occasionally fumed and interrupted — only to be cut off at times by Corker — Moniz emerged as the calm center of the proceedings, beginning his interjections with recitations of what he described as “facts,” and mildly observing that Republican characterizations were “incorrect.”

Although some Democrats raised specific questions, most were supportive and provided openings for witness affirmations that the deal is a good one.

“If you were bamboozled, the world has been bamboozled,” said Sen. Barbara Boxer (D-Calif.). “That’s ridiculous and it’s unfair and it’s wrong. You can disagree for sure with aspects of this agreement, but I think we need to stay away from that kind of rhetoric.”

Republicans and some Democrats complained about a side agreement between Iran and the International Atomic Energy Agency to resolve questions about past Iranian nuclear weapons at secret military sites. Although that agreement is referred to in the main deal, its specific terms are not part of it and the IAEA document is not available to either the administration or Congress.

Corker and Sen. Benjamin L. Cardin (Md.), the committee’s ranking Democrat, sent a letter to Obama this week saying it should be available for Congress to review.

In a news conference Thursday, House Speaker John A. Boehner (R-Ohio) again called the agreement “a bad deal.” Asked about the administration’s professed confidence that it could garner the votes to sustain a presidential veto, should Congress vote against the deal, Boehner said, “We’ll see.”

“The more we learn, the more questions we have,” he said. “You know, is America safer with a deal that provides the world’s biggest state sponsor of terror with more than $100 billion” in unfrozen assets and a potentially resurgent economy?

Lew provided a new assessment of how much money Iran would get if sanctions were lifted on its funds frozen around the world. “We estimate that after sanctions relief, Iran will only be able to freely access around half of these reserves, or about $50 billion,” he said, “and that’s because over $20 billion is committed to projects with China, where it cannot be spent, and tens of billions in additional funds are non­performing loans to Iran’s energy and banking sector.”

Many lawmakers, particularly among Republicans, voiced resentment of the clear implication by Kerry that they would be to blame if the deal collapsed.

“In the process of being fleeced, what you’ve really done here is you have turned Iran from being a pariah to now Congress, Congress being a pariah,” Corker said.