If the intelligence community and other technical experts conclude, once a final agreement is signed, that it does limit Iran’s breakout potential to a year, I think the administration can make a good case for it.
The administration faces two big hurdles, however, the American friends of Israel who are persuaded that the agreement is bad for Israel and Congress as an institution that will likely take destructive actions unless it can be given a constructive role.
As a first step, the administration should stop its punitive actions against Israel. They can be held in reserve pending future Israeli behavior. Next, the administration should reach out to American friends of Israel and to Israelis not in the Netanyahu government to see what steps might reassure Israel if the agreement is concluded and implemented. Maybe increased military aid would help. Maybe the U.S. should offer a formal defense treaty, something both sides have resisted in the past but which now might provide reassurances.
To deal with Congress, the administration should work out a deal giving Congress one or more votes on the agreement. The President has broad legal authority to sign and implement this kind of agreement without submitting it to a 2/3 Senate vote. But he should agree to allow an advisory vote by Congress and he should embrace a clear congressional vote on lifting sanctions. If the end result is a congressional vote criticizing the agreement and keeping US sanctions in place, the agreement could still go into effect; the US could still support a UN Security Council vote lifting sanctions; Iran would still be under pressure to comply with the agreement in order to get sanctions lifted by other countries. That messy situation still looks better to me than a collapse of the agreement blamed on the U.S. Congress.