The administration is trying hard to sell the recently-announced "nuclear framework" with Iran, though it is hard to tell yet if their arguments are having any affect on the many skeptics. It is a better proposed deal than many of us expected, but it is far, far from the president's promise of a couple of years ago to assure that Iran would not get nuclear weapons. At best, if no one cheats, it lets Iran get within a few months of weapon production. It does include an inspection regime, but it leaves almost all of Iran's extensive nuclear weapons infrastructure pretty much in place.
But if course this is just a "framework" so far, not a signed deal. And the devil is in the details. Within hours of the announcement, Washington and Iran were describing the deal in different, and even opposing, ways. The Republicans and even some Democrats are still skeptical. And within days Iran's supreme leader Ali Khamenei had publicly announced that he would accept no deal which didn't drop all sanctions the day the deal was signed, which is pretty much a non-starter for the US. So we are still a long, long way from a deal.
Fareed Zakaria makes a compelling case that one can only evaluate this deal in the light of the possible alternatives - continuing the sanctions or military intervention. Military intervention would be a major activity - Iran is not Iraq or Afghanistan and it's nuclear program won't be destroyed with just a few "surgical" air strikes. It would probably take a full-scale US invasion of Iran to really destroy the nuclear infrastructure, and most of the world would probably condemn the US for such an action. Sanctions haven't slowed Iran's nuclear program to date much, and wouldn't likely to do so in the future. Moreover, it is very hard to keep the sanctions in place - lots of nations would like to cheat and buy Iranian oil. So by Fareed's argument any deal is perhaps better than no deal.
But there is another side to this issue. Iran is in the process of sponsoring a massive Shia takeover of large parts of the Middle East through the surrogate jihadists it is arming and funding in places like Lebanon and Syria and Iraq and Yemen. Removing the sanctions on Iran frees massive financial resources which Iran can use to accelerate and increase its efforts to subvert the governments of its neighbors. In that respect a deal, while (perhaps) slowing Iran's nuclear weapons programs, would have undesirable effects elsewhere.
Then of course one must consider whether it really matters whether Iran gets a nuclear weapon. It may threaten Israel, but Iranian leaders know perfectly well that hitting Israel with nuclear weapons would result in their own major cities being reduced to radioactive dust within hours. And in fact an Iranian nuclear attack on just about any of their neighbors might well bring a nuclear response from the US and/or European nations. Like most authoritarian regimes, the survival of the regime itself is uppermost in their minds, and they are likely to be fairly pragmatic about that, whatever fanatical slogans they may chant in public.
Moreover, I am sure the Iranian leadership is perfectly well aware that if they are perceived, or even suspected, of having deliverable nuclear weapons, many of their neighbors in the Middle East will feel the need to acquire nuclear arms as well, which would in the end make Iran less secure. Saudi Arabia, for one, could afford to acquire nuclear weapons fairly quickly, and would probably do so.
It will be interesting to see how this plays out. It the deal is scuppered, it is still not clear which side's hard-liners will be the ones to kill the deal. Nor is it clear yet if Congress can successfully impose on the administration a requirement to get Congressional approval of any proposed deal. And it is still not clear if the president is willing to walk away from a defective agreement, or if his commitment to his "legacy" is so strong he will take any deal he can get.