President Joe Biden and Jordan’s King Abdullah II, speaking jointly at the White House on Monday, warned against an indiscriminate Israeli invasion of Rafah in southern Gaza, resulting in an event that had not occurred since the Israel-Hamas war began - the president standing alongside an Arab leader to voice reservations about the Israeli onslaught in the Palestinian enclave.

“The major military operation in Rafah should not proceed without a credible plan to ensure the safety and support of more than 1 million people sheltering there,” Biden said, referring to Israel’s publicly announced plans to invade the city. “Many people there have been displaced - displaced multiple times, fleeing the violence to the north. And now they’re packed into Rafah, exposed and vulnerable. They need to be protected.”

Abdullah was more direct. “We cannot afford an Israeli attack on Rafah. It is certain to create another humanitarian catastrophe,” the king said. Referring to the war more broadly, he added: “We cannot stand by and let this continue. We need a lasting cease-fire now. This war must end."

Biden himself has not publicly called for a cease-fire, saying Israel must be allowed to defend itself by rooting out and destroying Hamas’s base of operations in Gaza. But his willingness to stand alongside an Arab leader who did issue such a call was notable.

U.S. officials privately have told members of Congress that Israel is not close to eliminating Hamas, the stated goal of its military campaign, more than 100 days into the war, according to officials familiar with the briefing, who spoke on condition of anonymity to describe a private exchange.

The joint comments by the president and the king Monday came after Biden met privately with Abdullah at the White House, the first face-to-face discussion the president has held with an Arab leader since the Israel-Gaza war began in October. The meeting came as U.S. officials have expressed deep concern about Israel’s plans to target the tiny town of Rafah, which borders Egypt and where about 1.3 million Palestinians are living in decrepit conditions after fleeing there under Israeli orders.

Despite Biden’s growing willingness to publicly challenge Israel’s conduct of the war, he and his top aides have not publicly supported restricting aid to Israel or imposing conditions on it, as many of the president’s liberal critics demand. And while National Security Council spokesman John Kirby last week said an Israeli operation in Rafah “would be a disaster for those people, and we would not support it,” the White House has not threatened specific consequences if Israel proceeds with its plans.

An Israeli operation overnight Sunday in Rafah succeeded in rescuing two hostages, but it also killed at least 67 Palestinians, according to the Gaza Health Ministry, raising fears among Arab leaders that a sustained Israeli operation there could kill and injure thousands more. The planned Rafah operation has also escalated fears of a forced displacement of tens of thousands of Palestinians, as Arab leaders fear they will be pushed into Egypt - a goal that far-right Cabinet members of Israeli Prime Minister Benjamin Netanyahu’s government have openly embraced.

Biden reiterated Monday that he and his top aides are working urgently to negotiate a six-week pause in the fighting between Israel and Hamas in exchange for the release of the remaining Israeli hostages held by Hamas, saying that could lay the groundwork for a permanent end to the war.

At a time when Biden has faced increasing criticism from Arab-American and Muslim voters angry over his staunch support for Israel and what they describe as a lack of empathy for Palestinians, Biden found a welcome ally in Abdullah. The president took the opportunity to highlight the suffering of the Palestinians, saying they are facing “unimaginable pain” and adding, “It’s heartbreaking. Every innocent life [lost] in Gaza is a tragedy, just as every innocent life lost in Israel is a tragedy as well.”

Jordan, whose population includes a large proportion of ethnic Palestinians, will almost certainly be key to any long-term American vision for the Middle East. Biden has said the war in Gaza must be followed by planning for a Palestinian state - a notion forcefully rejected by Netanyahu - and the United States believes that will require a thorough reform of the Palestinian Authority, which governs part of the West Bank. Jordan, which borders both Israel and the West Bank, would be central to any such effort.

In recent days, Biden has shown more willingness to take aim at the Israeli military operation in Gaza, last week calling it “over the top,” his strongest rebuke to date. But for months, Arab leaders in the United States and the Middle East have felt Biden’s public comments allowed little room for criticism of the hard-hitting military campaign.

The conflict began on Oct. 7 of last year, when Hamas militants surged across Gaza border into Israel and killed about 1,200 people, largely civilians, who lived in nearby towns and kibbutzim. They also took some 250 hostages.

Israel since then has mounted a fierce retaliatory campaign in Gaza, killing more than 28,000 Palestinians so far, according to the Gaza Health Ministry. In addition, more than 80 percent of the territory’s residents have been displaced, and an Israeli siege has put hundreds of thousands of residents at risk of famine and disease.

Meanwhile, Israeli officials have resisted repeated U.S. calls to allow more humanitarian aid into the enclave. Adding to the challenges are Israeli protesters who have blocked aid trucks from getting in to Gaza through the country’s Kerem Shalom crossing into the enclave.

Abdullah, whose wife, Queen Rania, is Palestinian, is one of few people who can speak to Biden in detail about the suffering in Gaza, said Bruce Riedel, a senior fellow at the Brookings Institution who has worked on Middle East issues in multiple U.S. administrations.

Biden and Abdullah have known each other for more than 20 years and have deep affection for each other, according to aides to both men. As vice president, Biden oversaw the Iraq portfolio for the Obama administration and made more than a dozen trips to the country. On each of those trips – either on the way over or the way back home – Biden stopped in Amman to visit Abdullah, Riedel said.

In the first months of his presidency, Biden demonstrated support for the Jordanian king after his half-brother threatened to destabilize the monarchy. Biden called the king immediately after the incident and voiced his full backing, a move that earned the deep gratitude of the monarch, experts said.

That longstanding relationship gives Abdullah the rare ability to speak in detail to Biden about the immense suffering in Gaza and appeal to his compassionate side, Riedel said.

“Abdullah can talk about all these issues in a level of candor that few other Arab leaders can because he knows Biden – they’ve been around together for a long time,” Riedel said. “I think he can be much more direct and candid. Part of the king’s objective here is to appeal to the empathetic part of Joe Biden and get him to show some empathy with the Palestinian people, which Biden needs to do for his own domestic political reasons.”

The conflagration in the Middle East, which has already spread to engage several Iran-backed militias in the region, carries the risk of significant political consequences for Biden. Arab Americans in Michigan and elsewhere are organizing to defeat him, and polls suggest that younger voters and people of color are deeply unhappy with his handling of the war.

Abdullah’s visit to Washington comes at a precarious time in the conflict, when Biden is closer than ever to a breach with Netanyahu over the high civilian toll, disagreements over humanitarian aid, and Netanyahu’s rejection of a Palestinian state. More immediately, U.S. officials are highly concerned about Netanyahu’s announcement of the upcoming military operation in Rafah.

Biden, as he stood outside the White House awaiting Abduallah’s arrival, was asked if Netanyahu is listening to his advice.

He smiled broadly and said, “Everybody does.”

Abdullah’s trip to Washington is part of a tour to visit the United States, Canada, France and Germany, part of his effort to mobilize international support for an immediate ceasefire in Gaza, as well as the protection of civilians and for more humanitarian aid. Abdullah is also expected on Tuesday to meet senior administration officials, including Secretary of State Antony Blinken, as well as members of Congress.

Abdullah spoke to Biden about rising violence in the West Bank, as U.S. and Arab leaders fear another front in the war could open up as tension boils in that territory. More than 370 Palestinians - including about 100 children - have been killed in violent clashes in the West Bank, including East Jerusalem, according to the U.N. Office for the Coordination of Humanitarian Affairs.

The great majority have been killed by Israeli military forces, but some have been killed by violent settlers. Biden issued an executive order earlier this month that imposed sanctions on four West Bank settlers for violence against Palestinians.

The meeting on Monday was also the first visit since three U.S. military members were killed last month in an attack on an outpost in northeastern Jordan. Biden blamed Iranian-backed militias for the killings, which launched a round of retaliatory strikes.

Speaking to reporters Monday, Abdullah reiterated the position that the violence in the Middle East will not end without a two-state solution, calling for “an independent, sovereign and vital Palestinian state, with East Jerusalem as its capital ... living side-by-side with Israel.”