At his seaside office complex in Doha on Wednesday evening, the Qatari prime minister thought he had a deal. Hamas’s negotiators, led by a burly former lawmaker, had left the prime minister’s office, having given up on an 11th-hour demand that was the last major obstacle to a cease-fire in Gaza after 466 days of war.

Reporters had begun to assemble in an auditorium downstairs, expecting to witness the prime minister, Sheikh Mohammed bin Abdulrahman Al Thani, announce that he and other mediators had finally brokered a deal. Two American envoys joined Sheikh Mohammed as he prepared his statement.

Suddenly, there was a new problem, according to two people familiar with the negotiations.

In a room elsewhere on the sixth floor, the Israeli delegation, led by the heads of Israel’s two main intelligence agencies, had their own last-minute demand. Prime Minister Benjamin Netanyahu wanted to clarify the names of a handful of Palestinian prisoners whom Israel would release during the truce.

As his aides tried to resolve the final hitch, Sheikh Mohammed sat in his office with Brett McGurk, President Biden’s lead negotiator, and Steve Witkoff, the representative of President-elect Donald J. Trump, hoping that their efforts had not been wasted.

This account of the final days of negotiation is based on conversations with nine people involved in or briefed on the talks, some of whom spoke on condition of anonymity to discuss sensitive diplomacy.

The truce that was ultimately announced at the belated news briefing, hours after Israel’s new demand, was little different to versions promoted for most of the past year by mediators from Egypt, Qatar and the Biden administration, whose representatives met frequently with the warring parties in Cairo, Doha and several European capitals throughout 2024.

What pushed the deal over the line this past week was the unlikely partnership between the envoys of America’s current and future presidents, working in tandem with the Qatari prime minister in marathon late-night meetings. While Mr. Biden and Mr. Trump have competed for credit, the reality is that their representatives were both crucial to the final push, each using different approaches to push the Israeli leadership toward a deal while Sheikh Mohammed focused on Hamas.

Starting last Sunday, the Israeli and Palestinian delegations, as well as the two Americans, spent long days at the prime minister’s compound, close to the old market in downtown Doha. The delegations, which do not speak directly to each other, sat in different rooms on different floors, with Qatari and Egyptian officials passing messages between the two sides.

“They aren’t natural partners, but the combination of these three individuals, and the three worlds they represent, was the only thing that was going to get this done,” said Thomas R. Nides, a former U.S. ambassador to Israel. “You needed pressure from all sides — pressure from the Arab world, pressure from Biden, and pressure from Trump.”

It was Mr. McGurk, a veteran diplomat long focused on the Middle East, who has helped oversee U.S. mediation efforts since the opening weeks of the war and who helped craft the deal’s complicated details nearly a year ago. It was Mr. Witkoff, a real estate investor who plays golf with Mr. Trump, who was instrumental in persuading Israel to finally agree to the deal’s contents. And it was Sheikh Mohammed who persuaded Hamas to make key compromises, while providing both sides with the office space in which to wrangle the final details.

The deal they sealed provides for a pause of at least six weeks in the fighting, during which time Hamas has agreed to gradually release 33 of the hostages captured during the group’s raid on Israel at the start of the war on Oct. 7, 2023. In exchange, Israel has committed to gradually releasing roughly 1,000 Palestinian prisoners, some of whom are serving life sentences for murder, and allowing hundreds of thousands of displaced Gazans to return to their homes.

The deal is extremely similar to proposals that the two sides nearly agreed to between May and July 2024. Those talks broke down amid disputes about whether to forge a permanent or temporary truce, whether and how to allow displaced Gazans to return home, how and when Israeli troops might withdraw from Gaza, and the number of hostages Hamas might release in the first weeks of a truce.

As a result, the war dragged on, leading to the killing of tens of thousands more Palestinians, as well as several Israeli hostages.

Critics accused Mr. Netanyahu of sabotaging the talks to avoid a collapse of his governing coalition, which included lawmakers opposed to a deal. Others said that Hamas had intentionally prolonged the negotiations in the hope that Israel might become entrenched in a wider regional conflict with Hamas’s allies in Lebanon, Iran and Yemen. At times, Qatar refused to continue mediating, accusing both sides of halfhearted engagement.

Momentum returned after Mr. Trump’s re-election in November, even before the president-elect warned Hamas that there would be “all hell to pay” if the hostages were not released by his inauguration. He appointed Mr. Witkoff, who had no diplomatic experience but growing business relationships in Qatar, as his emissary in the Middle East. Mr. Witkoff had been playing golf with Mr. Trump in September during what law enforcement officials said was an attempt on the former and future president’s life.

Quietly, members of the Biden administration reached out to Mr. Witkoff to see if they could work together on the cease-fire talks, according to two people familiar with the conversations. Despite vast political chasms between their bosses, Mr. McGurk and Mr. Witkoff began to coordinate, sometimes talking several times a day, according to one of the people.

Still, wide gaps between Hamas and Israel remained. Shortly before Christmas, with just weeks left in the Biden presidency, Mr. McGurk returned despondently from a trip to Doha. He told the Qataris that he would not fly back unless Hamas made a clear signal of its interest in a deal, according to two people familiar with his thinking.

That moment came in the first days of January, according to two people involved in the process. Sheikh Mohammed persuaded Hamas to confirm the names of more than 30 hostages who would be released during the first six weeks of a truce, a long-awaited move that suggested the group was genuinely interested in a deal, the people said. The reason for Hamas’s shift remains unclear, but analysts say that Israel’s increasing dominance over Hamas’s main allies, Hezbollah and Iran, left the group feeling isolated, while its own losses on the battlefield in Gaza left it feeling weakened.

Mr. McGurk was informed of the breakthrough while attending his daughter’s birthday party at an indoor trampoline park on Jan. 4, according to two people familiar with the event. He left the party halfway through, immediately flying to Doha to meet Sheikh Mohammed, his Egyptian counterparts and Israeli negotiators. Mr. Witkoff joined him on Jan. 10, and the pair agreed with Sheikh Mohammed that the Americans would jointly focus on cajoling Israel while the prime minister would press Hamas.

The main remaining differences centered on the depth of a buffer zone that Israel sought to maintain within Gaza’s borders, as well as the number of prisoners to be exchanged for wounded and sick hostages.

It was a visit at short notice by Mr. Witkoff to Jerusalem last Saturday, the Jewish Sabbath, that brought a new breakthrough, according to four officials briefed on the meeting.

Mr. Witkoff sat with Mr. Netanyahu and senior Israeli officials in the prime minister’s Jerusalem office, with Mr. McGurk joining the discussion by telephone.

The two Americans pressed Mr. Netanyahu to soften on the last two big obstacles, according to a person familiar with the discussion. Mr. McGurk warned the Israeli leader that he risked losing his best chance of sealing a deal. Then Mr. Witkoff applied the necessary pressure, stressing to Mr. Netanyahu that Mr. Trump wanted this deal done, the person said.

After the meeting, Mr. Netanyahu seemed to have changed his attitude, four officials said. He immediately ordered his four top negotiators — including David Barnea, the head of Israel’s foreign intelligence agency, and Ronen Bar, Israel’s domestic spy chief — to Doha.

Over the next four days, Sheikh Mohammed hosted a marathon series of meetings, mostly in his personal office, as Hamas officials, Israeli negotiators, Egyptian intelligence officers and the two Americans spoke with him, sometimes until the small hours of the morning.

The Israeli and Hamas teams, based on different floors, never saw each other; they took turns entering the prime minister’s office for updates on their enemy’s latest position.

Progress was sometimes hindered by the nature of Hamas’s command structure, which required its leaders in Qatar to check certain details with their counterparts in Gaza, who are all in hiding and hard to reach.

Mr. McGurk and Mr. Witkoff also often checked in with their respective bosses; at times, Mr. McGurk was speaking with Mr. Biden while Mr. Witkoff, just yards away, was on the phone with Mr. Trump or his team, according to a person familiar with the scene.

“We were negotiating word by word, sentence by sentence and formula by formula,” said Mohammed Al-Khulaifi, a minister of state in the Qatari foreign ministry. “It becomes exhausting mentally and physically.”

The biggest breakthrough came close to midnight on Sunday night, according to three people familiar with the moment.

Sheikh Mohammed told the two Americans that the deal could be closed if Israel could make two more compromises, according to one of the people.

Mr. McGurk and Mr. Witkoff walked together down the corridor to the Israelis’ room, where the negotiators were already speaking by phone with Mr. Netanyahu. Joining the call, the Americans told the Israeli leader that a deal could be reached if he agreed to slightly increase the number of prisoners involved in the swap, as well as slightly decrease the depth of the buffer zone.

After a loud debate in Hebrew between Mr. Netanyahu and his team, they made the compromise.

The Americans returned to update Sheikh Mohammed.

“We will have a deal,” the Qatari leader told the envoys, according to the person familiar with the scene.

After a year of failure, around midnight on Sunday, they thought they had an agreement, subject to wrangling over small final details.

Still, Wednesday brought more hitches. With the news briefing scheduled for the evening, Hamas suddenly tried to reopen a discussion about how much land Israeli troops would continue to control along the border between Egypt and Gaza.

Then, after Egyptian and Qatari leaders had persuaded Hamas to back down, Israel pushed for greater clarity about which Palestinian prisoners would be released.

Thousands of miles away, in the Oval Office, Jake Sullivan, the national security adviser, sat with President Biden and Vice President Kamala Harris, awaiting news from Mr. McGurk.

Even as Sheikh Mohammed finally announced the deal on Wednesday night, the last prisoners’ identities were still being clarified by the two sides, according to a person familiar with the debate.

But Mr. McGurk and Mr. Witkoff felt confident enough to inform their bosses that a cease-fire would be reached, one person familiar with the scene said.

That final wrangling continued into Thursday, with Mr. McGurk and Mr. Witkoff finally leaving Qatar that night.

The deal was cemented — and so was one of the unlikeliest pairings in diplomatic history.

Aaron Boxerman and Ronen Bergman contributed reporting.

Orange juice from Florida. Whiskey from Tennessee. Peanut butter from Kentucky.

Canada is preparing for an all-out trade war with its closest ally and biggest trading partner, and the list of American goods that could be affected is long.

Canadian officials are preparing a three-stage plan of retaliatory tariffs and other trade restrictions against the United States, which will be put into motion if President-elect Donald J. Trump makes good on his threat to impose a blanket 25 percent tariff on all Canadian goods imported into the United States.

Canadian officials will wait until Mr. Trump has made his move — which he has said will be on his first day in office, Monday — and then start with imposing tariffs. They would mostly affect consumer goods worth 37 billion Canadian dollars ($25.6 billion), according to two senior government officials familiar with the plans.

They spoke on condition of anonymity to discuss details of plans meant to remain private for now.

Goal: Maximum political pain

The Canadian officials said their choice of goods was meant to be precisely targeted and aimed at political impact. They specifically want to focus on goods made in Republican or swing states, where the pain of tariffs, like pressure on jobs and the bottom lines of local businesses, would affect Trump allies.

Canada’s government hopes that those allies, including governors or members of Congress, would then pick up the phone and call Mr. Trump, intervening in favor of de-escalation.

Mélanie Joly, Canada’s foreign minister, who spent Thursday and Friday in Washington, met with a slew of Republicans to make her country’s case, including Senator Lindsey Graham of South Carolina, Senator Jim Risch of Idaho, and the Senate majority leader, John Thune of South Dakota.

Ms. Joly said she hoped her outreach to senior Republicans would persuade them to intervene to avert or limit a trade war and its negative impact on consumers and jobs on both sides of the border.

“My job here is to be able to talk about facts, and that comes before any threat of counter tariffs from our side,” Ms. Joly said in an interview with The Times on Thursday. “Because then the senators might say, ‘Well, why are we doing this? Why are we imposing tariffs? It’s affecting my own constituency.’”

But, she added, Canada was ready to forcefully defend its interests if necessary. “Never underestimate Canadians,’’ she said. “We fight very hard, and we’re very courageous. We are willing to be surgical and appropriate to have an impact on American jobs.”

Bracing for Mr. Trump’s first day in office and what it might bring for Canada, Prime Minister Justin Trudeau and his cabinet will be huddled together on Monday and Tuesday in what some are calling their “U.S. war room,” in order to be able to respond swiftly if U.S. tariffs are announced.

The detailed list of goods is closely held, but it includes dozens of consumer goods from various categories, such as food and beverages, as well as other types of daily products, including dishwashers and porcelain goods like bathtubs and toilets.

Depending on what Canadian goods Mr. Trump chooses to impose tariffs on, and the level of those tariffs, Canada’s second move would be to expand its own tariffs to more American products, impacting 150 billion Canadian dollars’ worth of imports from the United States.

As part of its strategy, the Canadian government is also looking at other measures that would restrict the export of Canadian goods to the United States, such as export quotas or duties to be shouldered by the American side. That type of measure would be reserved for particularly sensitive Canadian exports that the United States relies on, such as hydroelectric power from Quebec used to provide energy across New England.

Tariffs work more like a tax on goods and are usually passed on to consumers. They make imported goods more expensive, and that often means consumers stop buying them, ultimately hurting the foreign companies exporting them.

Trade restrictions like export quotas aim to limit the availability of an exported good, and are particularly effective when an importing nation doesn’t have easily accessible or sufficient alternative sources for that good.

Back from the brink

No matter how Canada’s counter tariffs or export restrictions are deployed, the goal will be the same: to pressure the Trump administration to step back from the president-elect’s vow to launch a devastating trade war on the United States’ neighbor.

The trading relationship between the two countries is enormous, with nearly $1 trillion in goods exchanged every year. The two nations are each other’s top trading partner.

Some cross-border industries are so integrated that tariffs would suddenly pose a major regulatory headache for many companies. A single vehicle, for example, crosses the U.S.-Canadian border up to eight times before it is fully assembled. Tariffs would immediately disrupt auto assembly lines across the United States and in Ontario, the auto industry’s heart in Canada.

And Canada exports vital commodities to the United States. Some 80 percent of Canada’s oil and 60 percent of its natural gas are exported to the United States. More than half of the oil imported into the United States comes from Canada.

A third and final level of escalation if a trade war between the U.S. and Canada escalates and which the Canadian government is eager to avoid would restrict the export of sensitive commodities worth hundreds of billions of dollars, including oil and gas, potash, uranium and critical minerals. All are exports that are crucial to the United States

Alberta, Canada’s oil-exporting powerhouse, has said it does not support measures that would impact its key industry. The rift between the province’s leadership and the rest of the country could become more consequential if Canada decides oil must be used as leverage against the United States.

Canada’s planning for a potentially prolonged U.S. trade war also includes supporting domestic industries, according to one of the senior officials.

The government is preparing for the possibility of financial bailouts for Canadian businesses that are badly hit by the U.S. tariffs, most likely on a case-by-case basis, the official said.

While mass bailouts or blanket funding for entire industries may not be on the table, the official said it would be unthinkable to allow a tariff war with the United States to wipe out thousands of jobs and businesses without the government stepping in to mitigate the blow.

The Federal Reserve has withdrawn from a network of global financial regulators focused on climate risk days before President-elect Donald J. Trump returns to power.

The central bank announced that it was formally joining the network in December 2020, shortly after President Biden was elected. The decision was met with praise from Democrats and skepticism from Republicans, who worried that increased attention to climate risk by financial regulators could have harmful impacts on American bank customers.

The group, known as the Network of Central Banks and Supervisors for Greening the Financial System, exists to help central banks and other regulators exchange ideas and research as they figure out how to account for climate-related risks in the financial sector. The network also aims to “mobilize mainstream finance to support the transition toward a sustainable economy.”

Fed officials said the decision to leave the network came after the group’s work had broadened.

“While the Board has appreciated the engagement with the N.G.F.S. and its members, the work of the N.G.F.S. has increasingly broadened in scope, covering a wider range of issues that are outside of the Board’s statutory mandate,” the Federal Reserve said in a statement on Friday.

The network did not immediately respond to a request for comment.

Five members of the Fed’s Board of Governors voted to withdraw from the network, including Fed Chair Jerome H. Powell. Two members abstained, including Adriana Kugler and Michael Barr, who recently announced that he would step down from his role as vice chair for supervision by Feb. 28.

The central bank’s move to join the network was a seen as a sign of its recognition that the Fed had to begin taking into account the impact of extreme weather events as they occur more frequently and pose a greater risk to the financial system. The Fed had been participating in the network informally for more than a year before it officially joined.

Days before the Fed formally became a member, a group of Republican lawmakers expressed skepticism about the Fed’s involvement with the network. Its recommendations “could significantly limit access to capital for crucial industries and place harmful restrictions on regulated entities,” the Republican lawmakers wrote in a letter to Fed officials in December 2020.