Any idea that a US abstention from a UN ceasefire resolution signified a drastically different attitude toward the Gaza war by the Biden administration lasted barely four days.

The UN Security Council resolution demanding a quick ceasefire, hostage release, and large-scale delivery of food supplies was passed last Monday. By Friday, the Washington Post was reporting on the newest consignment of billions of dollars worth of US bombs and planes for Israel.

The only difficulty, according to a person acquainted with the operation, was a delay of a few days in processing approval of 1,800 MK-84 2,000-lb (907-kg) bombs, which can crush an apartment building and leave an 11-meter-deep crater.

It is a destructive weapon that has reportedly been employed frequently by the Israeli air force, playing a substantial role in the estimated 33,000 death toll in Gaza since October.

The news that the nearly $4 billion-a year arms pipeline from the US to Israel remained in full uninterrupted flow drew a furious reaction from critics, who pointed to the irony of the Biden administration urging a ceasefire and the delivery of food aid into Gaza while supplying the weapons that fuel both the war and the humanitarian crisis.

“It’s like putting a Band-Aid over someone’s tiny finger cut while you’re continuing to stab them in the chest,” Rae Abileah, a Jewish American peace activist, said.

As a catastrophic hunger continues to take root in Gaza, administration officials have faced questions nearly daily about why ongoing US military aid is not being made conditional on a change in Israeli behaviour to limit the civilian death toll and greatly expand relief deliveries.

The conventional answer has been that the US government, while asking Israel to do more to protect the residents of Gaza, should do nothing to impede Israel’s ability to defend itself, a bedrock of US foreign policy for more than half a century.

Democrats of all colors, whether they accept the current policy or not, think that a change of course by the Biden administration on military shipments is highly unlikely, for both policy and political reasons.

“He is not going to do it. He really believes Israel has a right to defend itself, and he feels that in his heart,” said a former senior Biden administration official of the president, adding, “There is zero probability in my view.”

Joe Biden’s personal feeling of loyalty to Israel, formed over decades of intimate interaction with Israeli officials, is a significant part of the reason his government is so reluctant to change.

“Biden considers himself to be part of Israel’s story; he has been involved for so long,” said Aaron David Miller, a former state department negotiator on the Middle East now at the Carnegie Endowment for International Peace.

A important moment to watch, Miller added, would be on May 8, when the state department is set to make a formal assessment on whether Israel is in conformity with international humanitarian law.

“I would be stunned if the administration made a judgment that the Israelis are out of compliance—in large part because Gaza is not the only issue,” Miller added.

Administration officials refer to the fact that a big new war has not so far been started with Hezbollah in Lebanon as a triumph for US diplomacy, but the constant exchange of fire over Israel’s northern border is a reminder that the threat is still festering. Most observers foresee a serious war within a year.

Hezbollah would constitute a considerably more significant military challenge than Hamas, with a reputed arsenal of more than 100,000 missiles and rockets.

“If you begin this process of conditioning weapons, it will be seen as a very strong message to the world community that America no longer has Israel’s back,” the former senior official added.

“Hamas is the least of Israel’s problems. Putting limits on armaments would be a message to Hezbollah, to the Iranians, and to the Syrians and the Houthis, who are looking around and trying to see if they can break Israel apart.”

The Biden administration also feels that conditionality would not serve as leverage on Benjamin Netanyahu’s right-wing coalition, which galvanises its core supporters by rejecting Washington.

“The idea that the Israelis would simply roll over and say, We give up? I don’t buy it,” Miller said. “It’s not just Netanyahu. It’s the entire government; it’s the public, which does not prioritise assistance deliveries. They have not been exposed to the horrible humanitarian crisis in Gaza.”

The Israeli government would not just ignore US signals, political observers say. Netanyahu would go farther, most likely traveling to the US to make common cause with Republicans and imply that Biden had deserted Israel in the face of terrorism.

Netanyahu did the same to Barack Obama in 2015, when Republicans invited him to address a joint session of Congress. The current speaker, Michael Johnson, has said he plans to invite Netanyahu again at the height of an election year, an election in which the Israeli leader obviously prefers Donald Trump.

At home, Biden’s tangible support of Israel has alienated Arab-Americans, other minorities, and young and progressive Democrats, and as a result, it has jeopardised his hopes for winning the critical swing state of Michigan at the very least, and with it maybe the whole general election.

A policy U-turn now would not be assured to gain those votes back, while it would risk alienating the innately pro-Israel portions of the Democratic coalition.

“Within the Democratic coalition, there’s a very strong group of people, primarily American Jews, who would want a different government in Israel but remain committed to the support of Israel,” Henry Olsen, a senior fellow at the Ethics and Public Policy Center, said.

The last president to threaten to block weapons supplies to Israel was Republican Ronald Reagan, while the last Democratic president to seriously alienate Jewish Americans in his own party was Jimmy Carter, who authorised secret contacts in 1979 with the Palestinian Liberation Organization and paid an electoral price the following year, losing the 1980 election. “There are many key states, like Pennsylvania or Arizona, that have a small but sizable Jewish constituency,” Olsen added.

Progressive Democrats say that the size of the humanitarian tragedy and the consequences of potential US cooperation in it made such typical political calculations outmoded. The sheer scope of the catastrophe makes the impossible thinkable, they say.

“I think President Biden has surrounded himself with a lot of people who are hawkish, who are deeply aligned with the rightwing lobby of Aipac [the American Israel Public Affairs Committee, the main Israeli lobby in the US],” Usamah Andrabi, communications director for Justice Democrats, said. “He should instead align himself with the voters that got him elected in the first place.”