Biden “made clear the need for Israel to announce and implement a series of specific, concrete, and measurable steps to address civilian harm, humanitarian suffering, and the safety of aid workers”, the White House said in a readout of the call.

“He made clear that US policy with respect to Gaza will be determined by our assessment of Israel’s immediate action on these steps.”

A key Biden confidant had earlier urged him to use the leverage afforded by the huge military aid that Washington gives Israel – something Biden has resisted for the past six months.

“I think we’re at that point,” Chris Coons, a Democratic senator from the president’s home state of Delaware, told CNN.

If Israel began its long-threatened full-scale offensive in the southern city of Rafah, without plans for some 1.5 million people sheltering there, “I would vote to condition aid to Israel,” Coons said. “I’ve never said that before, I’ve never been there before,” he added.

Israel-Gaza war after 6 months – what are the issues now?

Biden also reportedly faces pressure from even closer to home – from first lady Jill Biden.

“Stop it, stop it now,” she told the president about the growing toll of civilian casualties in Gaza, according to comments by Biden himself to a guest during a meeting with members of the Muslim community at the White House, and reported by The New York Times.

Biden has supported Israel’s six-month-old war sparked by Hamas’s October 7 attack, but has increasingly voiced frustration with Israel’s right-wing premier over the soaring death toll and dire humanitarian situation in Gaza.

In his strongest statement since the war began, Biden said Tuesday that he was “outraged and heartbroken” by Israel’s killing of the seven aid workers, who included a US-Canadian citizen. Israel has said the deaths were unintentional.

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Humanitarian aid workers delivering food killed in Gaza in ‘unintentional’ air strike

Humanitarian aid workers delivering food killed in Gaza in ‘unintentional’ air strike

But Biden’s words have not been matched by any concrete steps to limit the billions of dollars in military aid that Washington supplies to its bedrock regional ally.

In a sign of business as usual, Biden’s administration approved the transfer of thousands more bombs to Israel on the same day as the Israeli strikes that killed the seven aid workers, The Washington Post reported on Thursday.

Many Democrats fear the controversy could hurt Biden’s chances of re-election in November against Republican Donald Trump, as Muslim and younger voters express their anger over Gaza.

A former senior aide to Barack Obama – the president under whom Biden served as vice-president – called for Biden’s actions to back his words.

Bodies of foreign aid workers killed in Israeli strike taken out of Gaza

“The US government is still supplying 2 thousand pound bombs and ammunition to support Israel’s policy,” Ben Rhodes, a former deputy national security adviser in Obama’s administration, wrote on X.

“Until there are substantive consequences, this outrage does nothing. Bibi [Netanyahu] obviously doesn’t care what the US says, it’s about what the US does.”

US voters are also increasingly turning against Israel’s Gaza offensive.

A majority of 55 per cent now disapprove of Israel’s actions, compared to 36 per cent who approve, according to a Gallup poll released on March 27.