JERUSALEM — On the eve of critical negotiations aimed at ending the war in Gaza, the United States finds itself in an unenviable position: relying on the goodwill of Israel and Hamas — which have resisted a deal for months — and fearing that another setback could trigger an Iranian attack that risks widening the conflict beyond anyone’s control.

       The warring parties all have incentives to upend the planned talks in Doha on Thursday, described by President Joe Biden’s aides as a “final stage” bid to end a war that has killed tens of thousands of Palestinians and to secure the release of hostages captured by Hamas on Oct. 7. There are 115 hostages still held in Gaza, Israeli officials say; more than 40 are already dead.

       Israeli Prime Minister Benjamin Netanyahu is under pressure from members of his far-right cabinet to reject what they call a “surrender deal,” and he has been accused by his critics, including some hostage families, of extending the war for his own political survival.

       Ghazi Hamad, a member of the Hamas negotiating team, confirmed to The Washington Post on Wednesday that the group will not attend the Thursday talks, accusing Netanyahu of using them “as a cover to continue his aggression against our people.”

       Looming over the negotiations are threats by Iran and Hezbollah — still seething over the twin assassinations of Hamas leader Ismael Haniyeh and top Hezbollah commander Fuad Shukr — to strike back against Israel and reestablish deterrence. Haniyeh, seen as a more pragmatic voice within the movement and a key negotiator, has been replaced as political chief by Yehiya Sinwar, the leader of Hamas in Gaza and an architect of the attack on Oct. 7, when militants killed some 1,200 people in southern Israel.

       Diplomats fear it could make the group more inflexible and less willing to compromise. “The trajectory of this crisis and future of this region now rests in hands of Iran; Hezbollah; Sinwar and Benjamin Netanyahu,” Aaron David Miller, a Middle East expert who has advised multiple Democratic and Republican administrations, said Tuesday on X. “It’s as a depressing thought as one might imagine.”

       The Biden administration and its mediating partners Qatar and Egypt called for the meeting in the hopes of resolving outstanding differences between the parties after new Israeli demands, according to four officials familiar with the process. Like others in this report, they spoke on the condition of anonymity to discuss sensitive matters.

       In the most recent negotiating session, held in Rome late last month, the officials said, Israel insisted on new terms that went beyond the scope of the framework announced by Biden on May 31. That proposal called for a six-week cease-fire and partial hostage release in its first phase, to be accompanied by the withdrawal of Israeli troops from populated areas and the free return to northern Gaza of civilians who had fled south to escape Israeli bombardment.

       Under its new demands, Israel would maintain indefinite military control over the Philadelphi Corridor along the Gaza-Egypt border, as well as the Rafah crossing, and would operate checkpoints between north and south Gaza to monitor the movement of displaced Gazans. Netanyahu has claimed that the changes are consistent with the original framework.

       On Wednesday, Biden’s regional envoy Amos Hochstein made clear that the United States had run out of patience with parties angling for better terms.

       “There’s no more time to waste, and there’s no more valid excuses from any party for any further delay,” Hochstein said during his visit to Lebanon, where he was dispatched to cool tensions between Israel and Hezbollah after months of escalating strikes and counterstrikes.

       White House officials were surprised and outraged by the timing of Haniyeh’s killing and said they were “deeply concerned” by an Israeli strike Saturday that killed at least 93 people at a school in Gaza City housing displaced Palestinians, according to rescue officials. Israel said it was a command-and-control node for militants.

       Yet the Biden administration has continued to rule out using its most powerful leverage over its closest Middle East ally: the conditioning of military aid.

       Over the last week, the Biden administration approved about $20 billion in new weapons sales to Israel, including missiles, warplanes and munitions, and authorized the provision of an additional $3.5 billion for Israel to spend on U.S. weapons and military equipment. It also approved continued funding for a controversial Israeli military battalion accused of committing gross violations of human rights, including the abuse of a 78-year-old Palestinian American man who died after being bound and gagged by the unit.

       Israel, in turn, has blamed Hamas for the stalled negotiations. The group “continues to set additional terms and has refused to reach an agreement,” David Mencer, a spokesperson in the Israeli prime minister’s office, said Wednesday. Yet officials familiar with the negotiations have said Hamas’s remaining requests, which involve matters such as how and when Israeli hostages and Palestinian prisoners would be released, are not viewed as significant roadblocks.

       Even within Israel there is sharp disagreement over Netanyahu’s handling of the talks and how the war in Gaza should end. On Monday, Defense Minister Yoav Gallant said in a statement that a hostage deal was a matter of “urgency,” and he thanked the United States for its “leadership and commitment to the issue.” He also blasted Netanyahu’s long-held goal of “total victory” over Hamas as “gibberish,” according to leaks in Israeli media.

       Netanyahu fired back at Gallant, accusing him of spreading an “anti-Israel narrative” that “harms the possibility of reaching a hostage release deal.”

       Behind the bluster, Netanyahu has evolved in his outlook toward the talks, according to an Israeli official familiar with his thinking. He “now understands that he needs a deal, that the country is in favor of a deal, that leaving the hostages behind would be a traumatic wound that Israel may not recover from.”

       Though Hamas has expressed public frustration with the talks and will not attend Thursday, Suhail Al Hindi, a member of its political bureau, said the group was not giving up on the process. Al Hindi said Hamas would reengage if it receives a “clear commitment” from the Israelis on its last proposal.

       One of the officials familiar with the negotiations said Hamas has informed mediators that it is willing to meet with them after the Thursday session if there are developments or a serious response from Israel.

       State Department deputy spokesman Vedant Patel said Tuesday that Qatari diplomats “have assured us that they will work to have Hamas represented.”

       “We fully expect these talks to move forward as they should,” said Patel.

       Yet the killing of Haniyeh could present an added obstacle, officials fear, given his previous status as the final decision-maker in Hamas’s political office and his intuitive understanding of what would be acceptable to Sinwar — believed by Israeli officials to be in hiding, surrounded by hostages, in the tunnels beneath Gaza.

       Haniyeh was key in negotiating the Hamas offer this summer, described as significant by U.S. officials because it appeared to meet the conditions set out in the framework agreement announced by Biden. At the time, the president said Israel had agreed to the terms.

       CIA Director William J. Burns, Qatari Prime Minister Mohammed bin Abdulrahman Al Thani and Egyptian intelligence chief Abbas Kamel will take part in the meeting Thursday, said officials familiar with the situation. White House Middle East adviser Brett McGurk is also expected in the region.

       Israel will be represented by David Barnea, the head of the Mossad, as well as Shin Bet chief Ronen Bar and Maj. Gen. Nitzan Alon. Most critically, according to Netanyahu’s office, they will have a mandate to negotiate, which has not always been the case over months of on-again, off-again talks.

       As Washington strives for a diplomatic breakthrough in Doha, it is also nervously watching the movement of military assets in Iran, which has promised to “punish” Israel for assassinating Haniyeh in a Tehran guesthouse. Though Israel has neither confirmed nor denied its role, it told U.S. officials immediately afterward that it was responsible.

       On Monday, the U.S. Navy deployed more vessels to the eastern Mediterranean Sea, where they will join a squadron of F-22 Raptors, naval cruisers and destroyers, and the USS Abraham Lincoln aircraft carrier — positioned to defend Israel from a possible attack by Iran and its proxies.

       In April, after a deadly Israeli strike near an Iranian diplomatic facility in Syria, Tehran launched more than 300 drones and missiles toward Israel, a large but well-choreographed assault that Israel was able to repel with help from a U.S.-led military alliance. How Iran might strike this time, and the extent to which its plans hinge on the outcome of talks in Doha, remain open questions.

       “What we have heard from Iran is that their retaliation has nothing to do with the negotiations, they are two separate files because the retaliation is a response to an attack on Iran’s sovereignty,” a Hamas official told The Post on Wednesday, speaking on the condition of anonymity because he was not authorized to brief the media.

       “But it is possible that if there were serious efforts for a cease-fire deal, the overall situation could improve,” he added.

       It is an assessment that Biden appears to share. When asked by reporters Tuesday if a Gaza cease-fire deal might persuade Iran to refrain from a retaliatory attack against Israel, he responded: “That’s my expectation.”

       Rubin reported from Tel Aviv, DeYoung from Washington and George from Beirut. Hazem Balousha in Cairo, Lior Soroka in Tel Aviv and Yasmeen Abutaleb in Washington contributed to this report.