Israeli officials promise that Netanyahu will fight on, but it is not clear how or in what forum.

“The prime minister has a responsibility to point out the flaws of an agreement that endangers Israel, the region and the world — and he will continue to do so,” one senior Israeli official vowed.

The same aides and allies say that Netanyahu is playing a longer game, that the deal is so unpopular now that the next president will abandon, change or undermine it. Republican candidates for president, including Donald Trump and Jeb Bush, have vigorously opposed the deal. Democratic front-runner Hillary Rodham Clinton announced support.

Finally, officials here predict that when the dust settles, Israel will receive a windfall in new, advanced weaponry — including the most modern aircraft and missile technology — from members of Congress eager to show their pro-Israel bona fides and demonstrate that they remain steadfast enemies of Iran, even if some may have backed Obama on the nuclear pact.