US Vice President Kamala Harris meets Monday with a key member of Israel's war cabinet and rival of Prime Minister Benjamin Netanyahu a day after she delivered Washington's sharpest rebuke yet over the Israeli offensive in Gaza.

Benny Gantz, Israel's former military chief, will also hold talks with National Security Adviser Jake Sullivan and Secretary of State Antony Blinken, underscoring signs of discord in the government of Netanyahu over the war with Hamas.

Right-wing hardliners in Netanyahu's cabinet have criticized Gantz's visit as the United States leans on ally Israel, which it supplies with billions of dollars in military aid, to agree to a ceasefire in Gaza and allow in more humanitarian relief.

Democrat Harris, 59, who is campaigning for a second term with President Joe Biden, called Sunday for an immediate ceasefire and used unusually strong language to criticize aid efforts.

"Given the immense scale of suffering in Gaza, there must be an immediate ceasefire," Harris said during an event in Selma, Alabama, to mark a historic civil rights march in 1965.

"The Israeli government must do more to significantly increase the flow of aid. No excuses," Harris said.

During the Israel-Hamas conflict, the White House has used Harris a number of times to trail stronger public statements on the Israel-Hamas conflict than the president, getting the message out while reducing diplomatic tensions.

The White House said Harris's meeting with Gantz was "part of our continued efforts to engage with a wide range of Israeli officials on the war in Gaza and planning for the day after."

They would "discuss the urgency of securing a hostage deal, which would allow for a temporary ceasefire, and the need to significantly expand and sustain aid flows into Gaza, given the dire humanitarian situation," it said.

  'Trojan horse'

 A ceasefire would meanwhile be a major domestic win for Biden to be able to trumpet during his State of the Union speech on Thursday.

Biden faces acute pressure in an election year over his steadfast support for Israel and over Gaza's soaring civilian death toll, which the health ministry there put at 30,534, mostly women and children.

Israel vowed to eliminate Hamas after its unprecedented October 7 attack on southern Israel that resulted in the deaths of around 1,160 people, according to an AFP tally of official figures.

In the Democratic primary in the key US swing state of Michigan, which has a large Muslim population, just over 100,000 people voted "uncommitted" as a protest vote over Gaza.

A Netanyahu critic and rival, Gantz joined the five-person war cabinet formed after October 7 in a bid to project unity but has in recent weeks pressed Netanyahu on an exit strategy for the war.

The former defense minister and chief of staff of the armed forces has rejected Netanyahu's stance that only military pressure on Hamas will allow the return of hostages, analysts and Israeli media reports say.

Gantz's US visit was criticized by Doudi Amsellem, minister of regional cooperation, in a post on social media platform X that said: "Mr Gantz, your entry into government was intended to create unity at a time of emergency, not to be a Trojan horse".

Gantz’s visit comes at a time of rising pressure on Netanyahu over the fate of hostages still held in Gaza, and from a resurgent anti-government protest movement.

Israel has said it believes 130 of the original 250 captives taken by Hamas remain in the besieged territory, but that 31 have been killed.