NEW YORK – It has been, in many ways, the most torturous decision of his career, says Rep. Jerrold Nadler – even more difficult than the decision to oppose the use of force in Iraq – one which kept him up many nights mulling over whether to support or oppose the Iran nuclear deal. Now that he’s made the decision to support the nuclear agreement with Iran, the personal attacks on his loyalty to Israel, from the Orthodox community in Borough Park in particular, are proving deeply distressing to him.

The congressman represents a large swath of New York City, from the largely liberal Upper West Side through conservative Brooklyn neighborhoods of Midwood and Borough Park, said to be the most Jewish congressional district in the country. He is the first Democrat from the New York area to support the Joint Comprehensive Plan of Action. As soon as Senator Chuck Schumer opposed the deal he too was attacked, but with allegations of dual loyalty with Israel.

Nadler says he worked hard to compartmentalize and keep political considerations at bay as he considered the nuclear deal. “When you’re dealing with issues of war and peace, that conceivably means life and death for many people, you have to try to ignore the political ramifications. It’s difficult to compartmentalize like that but that’s what’s important, not to worry about my next election.”

His mandate, he feels, is clear: “to prevent Iran from getting a nuclear bomb, which as Prime Minister Netanyahu said, is an existential threat to Israel.” But deciding whether the JCPOA is the most effective means to that end was not.

Nadler consulted with people on all sides of the issue: Israel’s Ambassador to the United States Ron Dermer (though not Netanyahu directly), leaders of AIPAC, former heads of Israeli intelligence including Ami Ayalon, Agudath Israel of America and constituents. President Barack Obama met with Nadler and wrote him a four-page letter detailing United States support for Israeli military superiority through foreign military financing and state-of-the-art technology. In the letter, Obama also assured him that Iranian violations of the agreement would be met with so-called unilateral and multilateral “snap-back sanctions.”

On Friday Nadler published a nearly 5,200-word statement explaining why he has concluded that supporting the “flawed” JCPOA is the better decision. His statement is peppered with references to his Jewishness and commitment to Israel.

Now what’s keeping him up at night is the personal attacks he is getting from Orthodox precincts. “Of course it hurts. It’s emotional,” he tells Haaretz.

“Most hurtful is people asserting, shouting, that somehow I am anti-Israel,” Nadler says. “I’ve been a supporter of Israel my whole life,” ever since he was a boy of 8 or 9 in Crown Heights and raised money for Israeli charities by holding out pushkes.

The congressman went on to detail some of his pro-Israel bona fides. He has visited more times than he can count, including twice last year. After a trip with AIPAC last summer, when he stayed on for a vacation with his wife, Nadler appeared on MSNBC defending Israel’s actions during the Gaza war.

As a teenager, Nadler was active in Mizrahi Hatzair, a youth group then affiliated with the larger B’nai Akiva youth movement, he said. He was being groomed for a leadership position, until he reflected on the organization’s motto: “Eretz Yisrael, Am Yisrael, al pi Torah,” or “The Land of Israel for the Jews according to the Torah.”

“I said to myself, at 16 or 17, ‘I don’t believe in theocracies,’” and so he stepped back from involvement with the group.

As a Columbia University student he headed the district of the Zionist Organization of America. At the time it was not as right-wing an organization as it is today, he said.

His professional pro-Israel political activism predates his time in Congress, to which he was first elected in 1992. As a New York State Assembly member, in 1981 he authored a resolution urging Congress to reject the sale of the advanced aircraft known as AWACS to Saudi Arabia, a deal vehemently opposed by Israel and the organized American Jewish community at the time.

He has also led the fight against BDS, Nadler told Haaretz. “I was the first person to take on the Ford Foundation 10 years ago, and got them to revise their guidelines so they wouldn’t fund organizations which support BDS. Now for people to say that I’m anti-Israel is personally insulting and factually incorrect.”

While he has received emails and phone calls of support, he said, vociferous attacks have come from the religiously and politically conservative precincts of Borough Park in particular. New York State Assemblyman Dov Hikind rented a double-decker bus on which he hung a sarcastic banner bearing Iranian Supreme Leader Ali Khamenei’s smiling visage thanking America, and parked it outside Nadler’s Manhattan office.

Hikind has also threatened to raise millions of dollars to fund the primary campaign of someone who can beat Nadler in the next election.

City Council member David Greenfield, who represents the same community, tweeted “BK constituents outraged at his support of Iran deal & believe he lied to us” when he said earlier that his mind was not yet made up.

“Someone said I turned my back on klal Yisroel [the Jewish people] in tweets, in speeches. We are told a rabbi in shul compared me to the rabbis who approached President Roosevelt and told him not to admit Jewish refugees” from the Holocaust to America, said Nadler.

Someone else described his decision as “one of the most tragic betrayals” of the Jewish people, relayed Nadler.

“The political consequences are concerning, but I had to. How could I live with myself If I voted against it knowing that would increase the chances of a bomb in Iranian hands? How could I do that?”

“What bothers me about this debate is its incivility, excoriating people as traitors or dual loyalists,” Nadler tells Haaretz.

“Instead of debating whether I made a right or wrong decision, what we’re hearing from Borough Park and other places is a certitude that I and others know what we’re doing is wrong, that what we’re doing is going to increase the threat to Israel, and I am doing it because I want to abandon the Jewish people. That’s beyond the pale.”

Today Nadler lives on Manhattan’s Upper West Side and attends a non-Orthodox synagogue. He’s been away on vacation since announcing his decision to support the Iran deal, and has not yet been buttonholed by constituents on the sidewalk.