A former treasury secretary under President Barack Obama, Lew has attracted criticism from within the GOP for his defense of the 2015 Iran nuclear deal, which Israel’s right-wing government and many Republicans vehemently opposed, and related efforts by Obama to de-escalate the long-volatile relationship between Washington and Tehran.

Lew’s hearing before the Senate Foreign Relations Committee coincided with a high-stakes appearance by Biden in Israel as furor grips the Middle East and threatens to worsen the violence. Wednesday’s proceedings opened with a plea from Sen. Ben Cardin (D-Md.), the chairman, who evoked the ghastly images that emerged of Hamas militants brutalizing Israeli civilians and soldiers in the group’s stunning cross-border attack on Oct. 7. “Now,” Cardin said, “is not the time to play political games.”

Moments later, Sen. James E. Risch (Idaho), the committee’s top Republican, detailed his “reservations” about Lew’s potential appointment as ambassador. He cited a 2018 opinion piece by Washington Post columnist Marc Thiessen, who served in the George W. Bush administration, that implied that Lew lied to Congress years ago about the Obama-era Iran negotiations. “It’s important we get the right person in this position,” Risch said, adding later that “holding hands with Iran under the table doesn’t work for me.”

Other committee Republicans, including Sens. Marco Rubio (Fla.) and Mitt Romney (Utah) complained about Lew’s suitability for the high-profile post, also referencing his past statements on Iran. Sen. Pete Ricketts (R-Neb.) said in an interview earlier this week that confirming Lew as ambassador would be “a slap in the face to Israel.”

Lew hit back against the accusations, saying that he had implemented the letter of the nuclear deal but nothing more.

“We negotiated with Iran to have them roll back their nuclear program, in exchange for which they would get access to money that was their money that we had frozen. All we did was facilitate that transaction,” he said. “My team went around the world, telling banks all over the world: ‘We did not lift the sanctions on terrorism. We did not lift the sanctions on human rights violations. We did not lift the sanctions on regional destabilization. Be careful.’ And Iran thought that kept them from getting what they thought they should get.”

The landmark nuclear deal restricted Iran’s enrichment of uranium in exchange for the loosening of U.S. sanctions. Tehran exceeded the deal’s limits on the quantity and quality of its enriched uranium production after President Donald Trump withdrew from the agreement.

At the time of the 2015 negotiations, Lew defended the deal publicly to pro-Israel audiences in the United States, where he was once heckled. And because the Treasury Department is charged with implementing sanctions policies, he presided over the loosening of the regime against Iran. The deal unlocked foreign investment in Iran and eased financing for the government. Backers encouraged that investment as part of ensuring that the agreement functioned as it was envisioned.

Lew, 68, who even before his term as Treasury Secretary served in the top echelon of the Obama and Clinton presidencies, is an unusually senior appointment for the role. He was Obama’s chief of staff and director of the Office of Management and Budget, a role he also served for President Bill Clinton, the last time the federal government ran a budget surplus. Under Obama, he was also a deputy secretary of state.

An Orthodox Jew, Lew also has long-standing connections to the American Jewish community. He has long backed a two-state solution for Israelis and Palestinians, a position he reiterated in his opening remarks Wednesday.

While Lew and some Democrats nodded to international concerns about the plight of Palestinian civilians in Gaza, where a humanitarian crisis is rapidly unfolding as Israeli forces waged a ferocious response to the Hamas attack, there was relatively little acknowledgment of Israel’s role in the mounting death toll.

Rather, much of the questioning centered on the Obama-era Iran deal, Lew’s statements about Iran, Israel’s right to attack Hamas, and whether Lew was sufficiently supportive of Israel.

Sen. Bob Menendez (D-N.J.), recently stripped of the committee’s chairmanship after being charged in an alleged corruption scheme, pressed Lew on the depth of his commitment to defending Israel.

“At the U.N., Israel is constantly vilified,” Menendez said. “It is constantly made the central focus when other countries of the world who have significant human rights violations go untouched.” Menendez faces federal charges of acting as a foreign agent for Egypt, an authoritarian regime that has used violence to repress political opposition and minority groups.

“I will be an advocate for doing the things the United States should do to protect Israel, including at the U.N.,” Lew told Menendez.

Lew sought to reassure senators of his bona fides. He was raised in a Zionist household, he said, referring to the Jewish nationalist movement that galvanized support and migration for the establishment of the Jewish state in 1948.

“This is not the time for us to be lecturing Israel on what they have to do to establish the security that they have a responsibility to provide,” Lew said. “I think they know they have to do it in a way that is consistent with minimizing the impact on innocent civilians,” he added. But previous U.S. wars have demonstrated that “it is very, very hard for there not to be collateral damage.”

Two Democratic senators raised concerns about the fate of Palestinian civilians in Israel’s military action in Gaza. But they spoke near the end of the hearing, after most of the other senators and much of the audience had departed.

Sen. Chris Van Hollen (D-Md.) said that in June he had visited the Kfar Aza kibbutz, one of the communities Hamas attacked earlier this month. He said he was horrified by the scale of the atrocities committed there.

“So yes, Israel not only has a right but it does have responsibility to defend itself and to go after Hamas,” Van Hollen said. “I think you would also agree, I just want to make sure as you take on this position, you agree that it’s both in America’s interest and Israel’s interest that the war be prosecuted in accordance with international law and the rules of war.”