With this agreement, said Mike Huckabee, President Barack Obama "will take the Israelis and march them to the door of the oven." Under it, said Ted Cruz, "The Obama administration will become the world's leading state sponsor and financier of radical Islamic terrorism."
Huckabee's comment was so over-the-top that Jeb Bush said it was "just wrong." Cruz's charge provoked an objection from Bobby Jindal, who is not normally a model of restraint.
But Dick Cheney outdoes them all in his new book, "Exceptional: Why the World Needs a Powerful America." The deal, he declares, will most likely lead to "the first use of a nuclear weapon since Hiroshima and Nagasaki."
The critics don't realize that the more extreme their characterizations the less credible they are. It's not hard to make the case that the deal is flawed and inadequate. But it's hard to pretend it is, as Cheney claims, "madness."
Two of the most interesting moments of the campaign came at the Family Leadership Summit in Ames, Iowa, in July, which several GOP presidential candidates attended. Interviewing Marco Rubio and later Cruz, Republican consultant Frank Luntz asked: "If it's that bad, why would this president do this?"
Rubio had a simple answer: "Because he wants a legacy. He is dying to build out exhibits for his presidential library." Cruz echoed him: "The answer is simple. They see this purely as a domestic political legacy and agenda."
Really? According to them, the accord is a catastrophic blunder that will empower Iran, stimulate terrorism and invite a genocidal attack on Tel Aviv. How would a presidential library turn that into a glittering triumph? How could signing articles of surrender elevate your place in history?
Cheney, hitting a familiar conservative theme, insists the Iran agreement is "tragically reminiscent" of the 1938 Munich agreement, under which British Prime Minister Neville Chamberlain allowed Nazi Germany to annex a portion of Czechoslovakia. The concession only emboldened Adolf Hitler.
But Obama, being familiar with Munich, may have noticed that 1) it didn't work and 2) Chamberlain has been notorious ever since as a foolish appeaser. If this deal has half the gruesome consequences the Republicans predict, he will spend his retirement years in disgrace, his name synonymous with monumental gullibility.
The claim that he is seeking a legacy rests on the assumption that the deal will work well enough, and long enough, to resemble a great achievement. If it's going to lead straight to disaster, Obama had nothing to gain by signing it.
Assuming the president set out to engage in futile appeasement, he had an odd way of going about it. The Munich agreement was drafted and signed in a matter of days. The Iran negotiations took two years. The Munich agreement was 522 words long. This one fills 159 pages.
Had the administration been willing to settle for simply giving Iran everything it wanted, the talks would have concluded quickly and the text would be very brief.
Cheney explains this deal as part of Obama's plan to disarm and weaken America. "He has dedicated his presidency to restraining us, limiting our power and diminishing us," he writes.
This would come as a surprise to Moammar Gadhafi, Osama bin Laden and Anwar al-Awlaki, the U.S. citizen and al-Qaida leader who was killed in a targeted strike the president approved.
It would be news to the more than 2,000 people killed by drones under Obama. It might evoke doubt among the Islamic State fighters in Syria and Iraq, who have been the target of thousands of U.S. air attacks over the past year. It would puzzle Robert Gates, a Republican who ran the Pentagon under Obama as well as George W. Bush.
If the deal were a craven surrender, you would expect some of Obama's national security aides to resign in protest. You wouldn't expect it to win the endorsement of people like Colin Powell, who was secretary of state under George W. Bush and chairman of the Joint Chiefs of Staff under George H.W. Bush.
All those facts don't mean the Iran deal is a good one. They do make it clear, though, that it's a good-faith effort that has to be taken seriously. You can pretend otherwise, but it takes a wild imagination.