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

Sen. Pete Ricketts (R-Neb.), a member of the Foreign Relations Committee, said in an interview that confirming Lew as ambassador would be “a slap in the face to Israel.” Other committee Republicans, including Sens. Marco Rubio (Fla.) and Bill Hagerty (Tenn.), also have complained about Biden’s choice for the high-profile post.

Sen. Tom Cotton (R-Ark.), an Iran hawk and member of the Senate Armed Services Committee, has tried to rally GOP opposition to Lew, Senate aides said. On Tuesday, Cotton circulated a 2018 op-ed that accused Lew of lying about the Obama administration’s dealings with Iran in previous testimony to Congress.

Tom Nides, who stepped down this summer as Biden’s top diplomat in Jerusalem, said Lew’s defense of the Iran nuclear deal is “irrelevant” to the ambassador job. “I defended the Iran deal!” he said in an interview, noting that he did so while in Israel. “Jack is immensely qualified for this job.”

The landmark nuclear deal saw Iran scale back its enrichment of uranium in exchange for the loosening of U.S. sanctions. Tehran resumed its uranium enrichment in pursuit of nuclear weapons 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. Those actions are likely to come under close scrutiny from Senate Republicans at the confirmation hearing.

Israeli Prime Minister Benjamin Netanyahu has aggressively opposed any diplomatic dealings or negotiations between Washington and Tehran. In 2015, he used a joint address to Congress to publicly deride Obama’s policy — a display Lew criticized after leaving office.

Biden has expressed robust support for Israel since Hamas militants in the Gaza Strip staged a stunning cross-border attack that set off a wider crisis in the region. But the relationship between the two allies has been periodically strained, with Biden most recently frustrated by Netanyahu’s far-right coalition’s efforts to degrade the powers of Israeli courts to hold the government in check. Biden denied Netanyahu a coveted White House audience for most of the year, only last month extending an invitation to visit before 2024.

The White House had also been trying to cultivate a deal in which Saudi Arabia would have recognized Israel, a sea change in Arab-Israeli relations.

Nides predicted that Lew would be confirmed despite what he characterized as “a few senators who will have some issues,” saying: “He cares deeply about Israel. He knows the policy. He speaks for the president … It’s not even a question.”

The Hamas attack on Oct. 7, targeting a string of towns in southern Israel, killed more than 1,400 Israelis and prompted a swift declaration of war from Netanyahu. Israel has retaliated over the past week, cutting off the flow of food, water, electricity and fuel to the Hamas-controlled Gaza Strip, and dropping thousands of bombs, killing more than 2,700 Palestinians, according to Palestinian health officials. Israeli forces are poised to launch a ground offensive.

Iran and Hezbollah, meanwhile, have warned they could intervene in a conflict that could quickly broaden.

“The country is at war, guys,” Nides said, chiding Lew’s naysayers. “We need our ambassador there. We need to be fully all hands on deck.”

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.

Allies say that Lew has a reputation as a genial problem-solver in a town filled with big egos, a pinch hitter who can be counted on to manage unwieldy bureaucracies and smooth thorny situations. And he would have a direct line to the White House, a key advantage in a nation that keeps careful watch over its unusual and influential place in American foreign policy, an Israeli diplomat said, speaking on the condition of anonymity to discuss the Israeli perspective on an American decision.

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.

Although Lew in previous posts has engaged with foreign governments, he has never served overseas.

The Foreign Relations Committee’s chair, Sen. Ben Cardin (D-Md.), said he was “very confident” Lew would be confirmed.