President Joe Biden spoke by phone with Israeli Prime Minister Benjamin Netanyahu Thursday amid growing domestic pressure to set conditions on US military support amid domestic outrage over the killing of seven aid workers in Gaza.

In their first call since Monday's Israeli strike that killed the employees of the US-based World Central Kitchen group, Biden was expected to express anger and urge Israel to do more to protect humanitarian staff and civilians.

"President Biden spoke with Prime Minister Benjamin Netanyahu of Israel today to discuss the latest developments in Israel and Gaza. A readout of the call will be issued soon," a White House official said.

As domestic fury over the Gaza war mounts in a US election year, Biden's political allies intensified calls for him to use the leverage afforded by the huge military aid that Washington gives Israel.

"I think we're at that point," Chris Coons, a Biden confidant and 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.

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.

'Outraged and heartbroken'

Biden has supported Israel's six-month-old war sparked by Hamas's 7 October 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.

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 reelection 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.

"The US government is still supplying 2 thousand pound bombs and ammunition to support Israel's policy," Ben Rhodes, a former deputy national security advisor 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, its about what the US does."

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

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