​​​​​​​WASHINGTON

At least 20 White House staffers have lambasted President Joe Biden for failing to enforce an ultimatum that Israel take "concrete measures" to improve the humanitarian crisis in the Gaza Strip, or risk restrictions on American arms deliveries.

The Oct. 13 warning was issued in a letter sent by Secretary of State Antony Blinken and Defense Secretary Lloyd Austin, which gave Israel 30 days to take specific steps to improve the situation, including allowing a minimum of 350 aid trucks to enter Gaza daily.

The deadline came and went with aid groups saying the situation in Gaza worsened during the course of the month, particularly in northern Gaza where Israeli forces have launched a sweeping campaign that has killed hundreds of civilians and cut off aid deliveries.

A coalition of eight aid groups said Israel "consistently failed" to facilitate aid, warning that "people are being starved in Gaza" because “Israeli military operations have denied them critical food aid and basic necessities, which has, in turn, caused conditions approaching famine for 800,000 Palestinian civilians across Gaza."

“You are running out of time to do the right thing, but decisive action could save precious lives in the next two months,” the staffers wrote, according to a copy of their letter obtained by the Politico news outlet.

It is the latest missive written by Biden staffers warning of the dangers of continuing the status quo vis-a-vis Israel. But the president has remained unmoved, vowing just last week as his deadline was nearing a rapid end that Washington's commitment to Israel's security remains "ironclad."

Nearly 44,000 people have been killed in Gaza since Israel launched its war on the besieged coastal enclave in retaliation for the Hamas-led cross-border Oct. 7, 2023 attack that killed an estimated 1,200 people. About 250 others were taken hostage in Gaza where more than 100 remain.

Israel's restrictions on the delivery of humanitarian assistance, which Gaza was highly reliant upon even before the war due to an Israeli blockade, has led to widespread and acute shortages of food, clean water and medicine.

A senior White House staffer who spoke to Politico said the staffers decided to sign the letter because of "legacy."

“If the course is continued, it will be a legacy of horror," the staffer told Politico.

The Senate is slated to vote Wednesday on joint resolutions of disapproval brought by Independent Sen. Bernie Sanders that seek to block more than $20 billion in offensive arms sales to Israel sought by the Biden administration.

That includes sales of Joint Direct Attack Munitions worth $262 million, more than $800 million in 120mm tank and high explosive mortar rounds, over half a billion dollars of military tactical vehicles and up to 50 new F-15IA fighter jets and 25 upgrade kits worth $18.82 billion.

"Reliable human rights monitors have rigorously documented numerous incidents involving these systems leading to unacceptable civilian death and harm," Sanders' office said in a September statement.

"The Administration’s own report pursuant to National Security Memorandum 20 (NSM-20) concluded that these weapons 'have been used by Israeli security forces since October 7 in instances inconsistent with its IHL [international humanitarian law] obligations or with established best practices for mitigating civilian harm,'" it added.

So far, just six of the chamber's 100 senators have said they would support the measure.

Sanders is expected to brief reporters at the Capitol later Tuesday.