Washington ? What does Israel do now that President Obama has won the congressional votes needed to implement an Iran nuclear agreement that Prime Minister Benjamin Netanyahu described as “a stunning historic mistake”?

This was always the danger of Netanyahu’s unyielding rhetorical stand against the Iran deal, and his politically divisive campaign to block it in Congress: What if he failed? Would the Israeli leader try to rebuild bipartisan relations in Washington, or would he double-down once again, by encouraging Republican presidential candidates to repudiate the deal if elected?

We don’t know Netanyahu’s answer yet, but that’s the stark dilemma he faces, after Obama this week pinned down the 34 Senate votes needed to sustain a veto of legislation rejecting the Iran deal. Obama played for keeps on what he views as the most important foreign policy issue of his presidency — and he won.

“There wasn’t a lot of high-fiving or backslapping here,” asserts one senior administration official. For all the hype surrounding the Senate vote count, it has been clear for weeks that the House had a comfortable margin to block any override of a veto. “A lot of the drama was fictionalized,” says the administration official. “Everyone knew how this would end.”

Obama’s campaign picked up momentum after he made pledges to some key pro-Israel Democrats. In an Aug. 19 letter to Rep. Jerrold Nadler of New York, Obama promised that “should Iran seek to dash toward a nuclear weapon,” the military option would “remain available.” In a Sept. 1 letter to Sen. Chris Coons of Delaware, Obama pledged interdiction of weapons shipments to Iranian-backed groups such as Hezbollah, along with other measures aimed at “countering Iran’s asymmetric threat to the region.” Sen. Bob Casey of Pennsylvania gained quiet assurances that Iran’s covert actions would be countered in like manner.

But Robert Satloff, the executive director of the pro-Israel Washington Institute for Near East Policy, argues that the White House’s outreach was more show than substance. “The bottom line is that the administration gave zero,” Satloff said in an interview. “It was a lot of nice verbiage, a lot of conditional verbs and adjectives, but they didn’t fix any of the flaws in the agreement.”

Netanyahu’s aides are now claiming that “they never really believed they could stop the deal in Congress — they only wanted to alert the world how dangerous Iran is,” according to a report Thursday by The Washington Post’s William Booth in Jerusalem. But that makes it all the more puzzling why Netanyahu waged his scorched-earth campaign, and what he will do now to recover.

Dennis Ross, a former administration official who knows Israeli leaders well, said in an interview that Netanyahu probably hasn’t decided yet on the best strategy. Ross says many Israeli military leaders are urging the prime minister to begin working on a joint U.S.-Israeli strategy based on the deal’s premise that Iran’s nuclear program will be indeed be frozen for 15 years. “How do you take advantage of those 15 years?” asks Ross.

But having walked so far out on a limb, the Israeli leader may not be ready to retreat toward pragmatism yet — at least not publicly. Pro-Israel lobbying groups such as AIPAC may hope to mend fences with Democratic members of Congress and restore bipartisan support for Israel, but hard-line Republicans, such as the wealthy casino owner and campaign contributor Sheldon Adelson, may want to push partisan politics even further — toward a realignment that portrays the GOP as Israel’s only reliable friend.

“Netanyahu doesn’t want to validate the Iran agreement,” insists Satloff. “The Israelis weren’t at the table, and they aren’t bound by what was agreed.” At the same time, he predicts that Netanyahu will gradually move to consolidate joint U.S.-Israeli deterrence measures against Iran.

Obama was criticized, even by some of his closest political allies, for what the administration official describes as “being too alienating or strident in our tone,” especially in his speech early last month at American University. Now that he has won the votes, Obama can think about the real challenge ahead — which is successful implementation of the Iran pact, whether Netanyahu likes it or not.

Columnist note: In a column for Aug. 28 titled “The Hillary Clinton email scandal that isn’t,” I cited the view of attorney Jeffrey Smith that there may not be any prosecutable criminal case in the inadvertent disclosure of classified material by Clinton and her aides. I should have noted that Smith was an adviser to Clinton’s 2008 campaign, in addition to being a former CIA general counsel.

— David Ignatius is a columnist for Washington Post Writers Group.