The Senate on Tuesday confirmed Jacob J. Lew as the next U.S. ambassador to Israel, filling a post that the Biden administration has argued is critical to efforts to help the country as it seeks to topple Hamas in the Gaza Strip and ward off additional challenges from other Iran-linked groups in the region.
The 53-to-43 vote reflected a deep partisan divide over whether Mr. Lew, who served as Treasury secretary during the Obama administration, was the right man for the job. Only two Republicans, Senators Lindsey Graham of South Carolina and Rand Paul of Kentucky, joined all Democrats in backing Mr. Lew’s confirmation.
Mr. Lew’s confirmation comes as Congress is rushing to respond to Hamas’s Oct. 7 attack on Israel and the ensuing war in Gaza with a comprehensive package of emergency military and humanitarian assistance. President Biden has requested a $105 billion national security spending package for the war efforts in Israel and Ukraine, as well as threats in the Indo-Pacific and along the U.S.-Mexico border.
The task has been complicated by partisan divisions between the Democratic-led Senate, which is working to fulfill Mr. Biden’s request, and the G.O.P.-led House. The new speaker, Mike Johnson, Republican of Louisiana, has chosen instead to put forward a security assistance bill for Israel alone and package it with a provision to roll back an I.R.S. enforcement initiative that was part of Mr. Biden’s deficit reduction measure.
Though Mr. Biden nominated Mr. Lew before the war broke out, the urgency surrounding his confirmation has increased as the hostilities between Israel and Gaza have escalated. But while Republicans acknowledged the need to install a Senate-confirmed ambassador to the post, they rallied against Mr. Lew’s candidacy, arguing that his work promoting and carrying out a multinational nuclear pact with Iran during the Obama years had rendered him an untrustworthy interlocutor with Israel.
Republicans and Israeli officials vehemently opposed the Iran deal, which eased certain sanctions in exchange for Tehran giving up its nuclear ambitions, when it was struck in 2015. President Donald J. Trump later withdrew the United States from the pact.
“A vote for him is a vote to subvert, not strengthen, our ally in its time of need,” Senator Tom Cotton, Republican of Arkansas, said of Mr. Lew on the Senate floor.
“He lacks either the nerve or the will to really stand up for Israel when it really matters and the chips are down, as they are today,” Mr. Cotton added.
Democrats have consistently defended Mr. Lew, insisting that his conduct as Treasury secretary was above reproach and that his support for Israel is undeniable.
“Mr. Lew has a strong, long, proven record as a strong public servant and ferocious ally of Israel,” Senator Chuck Schumer, the majority leader, said on the floor on Tuesday. He also asserted that “the need to confirm Mr. Lew is plain and irrefutable: Israel is in crisis, America needs to stand with her, and a most urgent and obvious step would be to ensure that we have an ambassador in place.”
Republicans argued that Mr. Lew acted beyond his authority to try to ingratiate Iran into the international banking system by leaning on banks to do business with Tehran. They also accused him of trying to funnel money into Iran’s coffers and of working to undermine Israel’s interests at the United Nations.
“The underlying problem here is our policy and policies toward Iran,” said Senator Jim Risch of Idaho, the top Republican on the Foreign Relations Committee. He argued that given Iran’s key role as a financier of Hamas and other groups in the region challenging Israel, “the last thing we need is somebody who is very contrary to our view on how Iran should be handled.”
Democrats said the Israelis themselves backed Mr. Lew.
“They are very much looking forward to having a confirmed ambassador from the United States in Jerusalem to help in regards to the challenges they’re now facing as a result of Hamas’s terrorist attack in Israel, and they’re very much looking forward to Jack Lew being that ambassador — they told us that directly,” said Senator Benjamin L. Cardin, Democrat of Maryland and the chairman of the foreign relations panel.
He added that Mr. Lew’s experience working on prisoner releases could prove critical as the United States seeks to free American and Israeli hostages being held by Hamas.